07 Momentum
330 minutes
330 marks
Q1.
(a) The amount of damage caused when a car collides with a wall depends on the
amount of energy transferred.
If the speed of a car doubles, the amount of energy transferred in a collision
increasesfour times.
Explain, as fully as you can, why this is so.
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(3)
(b)
The diagram shows a car and a lorry about to collide.
When they collide, the two vehicles become tightly locked together.
(i)
Calculate the speed of the vehicles immediately after the collision.
(Show your working. There is no need to change to standard units.)
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Answer ....................................... km/h
(6)
(ii)
The collision between the car and the lorry is inelastic.
Explain, in terms of energy, what this means.
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(1)
(Total 10 marks)
Q2.
(a) When an object is moving it is said to have momentum.
Define momentum.
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(1)
(b)
The diagram below shows one way of measuring the velocity of a bullet.
A bullet is fired into a block of wood suspended by a long thread.The bullet stops in the
wooden block.The impact of the bullet makes the block swing.The velocity of the wooden
block can be calculated from the distance it swings.
In one such experiment the block of wood and bullet had a velocity of 2
m/simmediately after impact. The mass of the bullet was 20 g and the mass of the
wooden block 3.980 kg.
(i)
Calculate the combined mass of the block of wood and bullet.
........................................................................... Mass ....................................
(1)
(ii)
Calculate the momentum of the block of wood and bullet immediately after impact.
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…...................................................................... Momentum ............................
(3)
(iii)
State the momentum of the bullet immediately before impact.
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(1)
(iv)
Calculate the velocity of the bullet before impact.
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……................................................................. Velocity ........................... m/s
(3)
(v)
Calculate the kinetic energy of the block of wood and bullet immediately
after impact.
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…….............................................................. Kinetic energy ......................... J
(3)
(vi)
The kinetic energy of the bullet before the impact was 1600 joules. This is much
greater than the kinetic energy of the bullet and block just after the impact.What has
happened to the rest of the energy?
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(1)
(Total 13 marks)
Q3.
The drawing below shows two railway trucks A and B, moving in the same direction.
TruckA, of mass 1500 kg, is initially moving at a speed of 8 m/s. Truck B, of mass 2000 kg, is
initially moving at a speed of 1 m/s.
Truck A catches up and collides with truck B. The two trucks become coupled together as
shown in the diagram.
(a)
Calculate:
(i)
the initial momentum of truck A.
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......................................................... momentum ................................... kg m/s
(ii)
the initial momentum of truck B.
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......................................................... momentum ................................... kg m/s
(iii)
the total momentum of the trucks before the collision.
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................................................. total momentum ................................... kg m/s
(6)
(b)
Calculate the speed of the coupled trucks after the collision.
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(5)
(c)
(i)
How is the total kinetic energy of the trucks changed as a result of the collision?
A calculated answer is not needed for full marks.
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(ii)
State an energy transfer which accounts for part of the change in the total kinetic
energy of the trucks during the collision.
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(iii)
What would have been the effect on the change of total kinetic energy of the trucks
if the collision had been more elastic?
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(3)
(Total 14 marks)
Q4.
(a)
How can the momentum of an object be calculated?
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(2)
(b)
In a collision momentum is always conserved. What does this mean?
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(2)
(c)
Two trolleys are placed on a frictionless runway as shown in the diagram below. Trolley A
has a protruding pin, and trolley B is fitted with a piece of soft cork so that the trolleys will
stick together after colliding.
Trolley A has a mass of 2 kg, and trolley B has a mass of 1 kg. Trolley B is stationary.
Trolley A strikes trolley B at a speed of 6 m/s. Both trolleys then move to the right
together.
(i)
Calculate the speed at which trolleys A and B jointly move after the collision.
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(4)
(ii)
Calculate the change in kinetic energy which occurs during the collision.
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(4)
(Total 12 marks)
Q5.
The diagram below shows two balls on the bowling green. Ball A is moving with a velocity of
4 m/s, and is about to collide with ball B which is stationary. Both balls have a mass of
1.5 kg.
After the collision both balls move to the right but the velocity of A is now 1 m/s.
(a)
(i)
Calculate the momentum of ball A just before the collision.
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Answer ...................... kg m/s
(1)
(ii)
What is the total momentum of balls A and B after the collision?
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Answer ....................... kg m/s
(1)
(iii)
Calculate the momentum of ball A just after the collision.
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Answer ....................... kg m/s
(1)
(iv)
Calculate the momentum of ball B just after the collision.
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Answer ....................... kg m/s
(1)
(v)
Calculate the velocity of ball B just after the collision.
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Answer ............................ m/s
(1)
(b)
Calculate the loss of kinetic energy in the collision.
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Answer ............................... J
(3)
(Total 8 marks)
Q6.
(a) The diagram shows a car being driven at 14 rn/s. The driver has forgotten to clear a
thick layer of snow from the roof.
Which of the following has the smallest momentum? Draw a circle around your answer.
the car
the driver
the snow
Give a reason for your answer.
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(2)
(b)
Seeing an obstacle in the road, the driver applies the car brakes. The car slows down in a
straight line.
(i)
Does the momentum of the car increase, decrease or stay the same?
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Give a reason for your answer.
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(2)
(ii)
As the car slows down the snow starts to slide. In which direction will the snow start
to slide, backwards, forwards or sideways?
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Give a reason for your choice of direction.
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(2)
(c)
Draw a circle around the unit which can be used to measure momentum.
Nm
J/s
Ns
(1)
(Total 7 marks)
Q7.
(a) The picture shows two ice hockey players skating towards the puck. The players,
travelling in opposite directions, collide, fall over and stop.
(i)
Use the following equation and the data given in the box to calculate the momentum
of player number 3 before the collision. Show clearly how you work out your answer
and give the unit.
momentum = mass × velocity
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Momentum of player 3 = .......................................
(3)
(ii)
What is the momentum of player 4 just before the collision?
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(1)
(iii)
The collision between the two players is not elastic. What is meant by
an elasticcollision?
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(1)
(b)
The pictures show what happened when someone tried to jump from a stationary rowing
boat to a jetty.
Use the idea of momentum to explain why this happened.
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(2)
(c)
The diagram shows one type of padded body protector which may be worn by a horse
rider.
If the rider falls off the horse, the body protector reduces the chance of the rider being
injured. Use the idea of momentum to explain why.
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(3)
(Total 10 marks)
Q8.
The picture shows luggage which has been loaded onto a conveyor belt.
Each piece of luggage has a different mass.
Mass of A = 22 kg
(a)
(i)
mass of B = l2 kg
mass of C = 15 kg
What is the momentum of the luggage before the conveyor belt starts to move?
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Give a reason for your answer.
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(2)
(ii)
When the conveyor belt is switched on the luggage moves with a constant speed.
Which piece of luggage A, B or C has the most momentum?
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Give a reason for your answer.
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(2)
(iii)
At one point the conveyor belt turns left. The luggage on the belt continues to move
at a constant speed.
Does the momentum of the luggage change as it turns left with the conveyor belt?
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Give a reason for your answer.
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(2)
(b)
Draw a circle around the unit which can be used to measure momentum.
J/s
kg m/s
Nm
(1)
(Total 7 marks)
Q9.
(a)
What is the principle of conservation of momentum?
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(2)
(b)
The diagram shows a simplified aircraft jet engine.
Adapted from GCSE Physics by Tom Duncan. John Murray (Publishers) Ltd.
(i)
What is the function of the turbine?
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(1)
(ii)
Explain how the engine produces a forward thrust.
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(4)
(c)
During flight, air enters the engine at 175 m/s and leaves at 475 m/s. A forward thrust of
105 kN is produced.
Use the following equation to calculate the mass of air passing through the engine every
second. (Ignore the mass of the burned fuel.)
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Mass of air = ............................................... kg
(2)
(Total 9 marks)
Q10.
(a) When two objects collide, and no other forces act, then conservation of
momentumapplies.
(i)
What does the term conservation of momentum mean?
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(2)
(ii)
Apart from collisions and similar events, give another type of event in
whichconservation of momentum applies.
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(1)
(iii)
Write, in words, the equation which you need to use to calculate momentum.
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(1)
(iv)
The diagram shows a straight and horizontal runway and two trolleys, X and Y,
which can move on the runway.
X has a mass of 0.2 kg and its velocity is 1.2 m/s to the right. Y has a mass of 0.1 kg
and is stationary. When X collides with Y they stick together.
Calculate the velocity of the trolleys after the collision.
Show clearly how you work out your answer and give the unit and direction.
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Velocity of the trolleys = ......................................................................
(5)
(v)
What assumption did you make in order to calculate your answer to part (a)(iv)?
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(1)
(b)
Just before it hits a target, a bullet has a momentum of 5 kg m/s. It takes 0.00125 s for the
target to stop the bullet.
Calculate the force, in newtons, needed to do this.
Write, in words, the equation that you will need to use and show clearly how you work out
your answer.
Force = ................................................ newtons
(3)
(Total 13 marks)
Q11.
(a) The diagram shows a hammer which is just about to drive a nail into a block of
wood.
The mass of the hammer is 0.75 kg and its velocity, just before it hits the nail, is 15.0 m/s
downward. After hitting the nail, the hammer remains in contact with it for 0.1 s. After this
time both the hammer and the nail have stopped moving.
(i)
Write down the equation, in words, which you need to use to calculate momentum.
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(1)
(ii)
What is the momentum of the hammer just before it hits the nail?
Show how you work out your answer and give the units and direction.
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Momentum = ...................................................................
(3)
(iii)
What is the change in momentum of the hammer during the time it is in contact with
the nail?
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(1)
(iv)
Write down an equation which connects change in momentum, force and time.
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(1)
(v)
Calculate the force applied by the hammer to the nail.
Show how you work out your answer and give the unit.
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Force = ............................................................................
(3)
(b)
A magazine article states that:
“Wearing a seat belt can save your life in a car crash.”
Use your understanding of momentum to explain how this is correct.
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(4)
(Total 13 marks)
Q12.
The roads were very icy. An accident was recorded by a security camera.
Car A was waiting at a road junction. Car B, travelling at 10 m/s, went into the back of car A.
This reduced car B’s speed to 4 m/s and caused car A to move forward.
The total mass of car A was 1200 kg and the total mass of car B was 1500 kg.
(i)
Write down the equation, in words, which you need to use to calculate momentum.
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(1)
(ii)
Calculate the change in momentum of car B in this accident.
Show clearly how you work out your final answer and give the unit.
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Change in momentum = .........................................
(3)
(iii)
Use your knowledge of the conservation of momentum to calculate the speed, in m/s, of
car A when it was moved forward in this accident.
Show clearly how you work out your final answer.
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Speed = ............................................................ m/s
(3)
(Total 7 marks)
Q13.
The diagram shows a small, radio-controlled, flying toy. A fan inside the toy pushes air
downwards creating the lift force on the toy.
When the toy is hovering in mid-air, the fan is pushing 1.5 kg of air downwards every10
seconds. Before the toy is switched on, the air is stationary.
(a)
Use the equations in the box to calculate the velocity of the air when the toy is hovering.
momentum = mass × velocity
force =
Show clearly how you work out your answer.
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Velocity = ................................................. m/s
(3)
(b)
Explain why the toy accelerates upwards when the fan rotates faster.
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(2)
(c)
The toy is not easy to control so it often falls to the ground.
Explain how the flexible polystyrene base helps to protect the toy from being damaged
when it crashes into the ground.
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(3)
(Total 8 marks)
Q14.
The diagram shows the forces on a small, radio-controlled, flying toy.
(a)
(i)
The mass of the toy is 0.06 kg.
Gravitational field strength = 10 N/kg
Use the equation in the box to calculate the weight of the toy.
weight = mass × gravitational field strength
Show clearly how you work out your answer and give the unit.
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Weight = .................................................
(3)
(ii)
Complete the following sentence by drawing a ring around the correct line in the
box.
When the toy is hovering stationary in mid-air, the lift force is
bigger than
the same
as
the weight of the
toy.
smaller
than
(1)
(b)
When the motor inside the toy is switched off, the toy starts to accelerate downwards.
(i)
What does the word accelerate mean?
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(1)
(ii)
What is the direction of the resultant force on the falling toy?
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(1)
(iii)
Does the momentum of the toy increase, decrease or stay the same?
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Give a reason for your answer.
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(2)
(Total 8 marks)
Q15.
In an experiment at an accident research laboratory, a car driven by remote control was
crashed into the back of an identical stationary car. On impact the two cars joined together and
moved in a straight line.
(a)
The graph shows how the velocity of the remote-controlled car changed during the
experiment.
(i)
How is the velocity of a car different from the speed of a car?
...........................................................................................................................
(1)
(ii)
Use the graph to calculate the distance travelled by the remote-controlled car before
the collision.
Show clearly how you work out your answer.
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Distance = ............................................... m
(2)
(iii)
Draw, on the grid below, a graph to show how the velocity of the second car
changed during the experiment.
(2)
(iv)
The total momentum of the two cars was not conserved.
What does this statement mean?
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(1)
(b)
The graph line shows how the force from a seat belt on a car driver changes during a
collision.
Scientists at the accident research laboratory want to develop a seat belt that produces a
constant force throughout a collision.
Use the idea of momentum to explain why this type of seat belt would be better for a car
driver.
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(2)
(Total 8 marks)
Q16.
The picture shows two children, X and Y, skating towards each other at an ice rink.
The children collide with each other, fall over and stop.
(a)
Before the collision the children had different amounts of kinetic energy.
(i)
What are the two factors that determine the kinetic energy of the children?
1 ........................................................................................................................
2 ........................................................................................................................
(2)
(ii)
What was the total kinetic energy of the children after they had fallen over and
stopped?
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(1)
(b)
The total momentum of the children before and after the collision is zero.
(i)
Use the equation in the box and the data given in the diagram to calculate the
momentum of child Y before the collision.
momentum = mass × velocity
Show clearly how you work out your answer.
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Momentum = ............................................... kg m/s
(2)
(ii)
Complete the following sentence using one of the words in the box.
conserved
decreased
increased
The total momentum of the two children was ..................................................
(1)
(Total 6 marks)
Q17.
The diagram shows a child on a playground swing.The playground has a rubber safety
surface.
(a)
The child, with a mass of 35 kg, falls off the swing and hits the ground at a speed of 6 m/s.
(i)
Use the equation in the box to calculate the momentum of the child as it hits the
ground.
momentum = mass × velocity
Show clearly how you work out your answer and give the unit.
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Momentum = ............................................................
(3)
(ii)
After hitting the ground, the child slows down and stops in 0.25 s.
Use the equation in the box to calculate the force exerted by the ground on
the child.
force =
Show clearly how you work out your answer.
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Force = ............................................................ N
(2)
(b)
The diagram shows the type of rubber tile used to cover the playground surface.
Explain how the rubber tiles reduce the risk of children being seriously injured when they
fall off the playground equipment.
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(3)
(c)
The ‘critical fall height’ is the height that a child can fall and not be expected to sustain a
life-threatening head injury.A new type of tile, made in a range of different thicknesses,
was tested in a laboratoryusing test dummies and the ‘critical fall height’ measured. Only
one test was completed on each tile.
The results are shown in the graph.
The ‘critical fall height’ for playground equipment varies from 0.5 m to 3.0 m.
Suggest two reasons why more tests are needed before this new type of tile can be
usedin a playground.
1 ..................................................................................................................................
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2 ..................................................................................................................................
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(2)
(d)
Developments in technology allow manufacturers to make rubber tiles from scrap car
tyres.
Suggest why this process may benefit the environment.
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(1)
(Total 11 marks)
Q18.
The diagram shows a child on a playground swing.
(a)
The playground surface is covered in rubber safety tiles. The tiles reduce the risk
ofserious injury to children who fall off the swing.
The graph gives the maximum height that a child can fall onto rubber safety tiles
ofdifferent thicknesses and be unlikely to get a serious head injury.
(i)
Describe how the maximum height of fall relates to the thickness of the rubber
safety tile.
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...........................................................................................................................
(1)
(ii)
The maximum height of any of the playground rides is 2 metres.
What tile thickness should be used in the playground?
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Give a reason for your answer.
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(2)
(b)
Use phrases from the box to complete the following sentences.
the force on
(i)
the work done to stop the time taken to stop
Falling onto a rubber surface compared to a hard surface increases
............................................................ the child.
(1)
(ii)
Momentum is lost more slowly falling onto a rubber surface than on a hard surface.
This reduces ............................................................ the child.
(1)
(Total 5 marks)
Q19.
(a) The diagram shows three skiers, X, Y and Z, on a moving chairlift.The mass of each
skier is given in the table.
Which one of the skiers, X, Y or Z, has the most momentum?
.....................................................................................................................................
Give the reason for your answer.
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(2)
(b)
At one point in the journey, the chairlift accelerates to a higher speed.
What happens to the momentum of the three skiers as the chairlift accelerates?
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(1)
(Total 3 marks)
Q20.
(a)
The diagram shows an athlete at the start of a race. The race is along a straight
track.
In the first 2 seconds, the athlete accelerates constantly and reaches a speed of 9 m/s.
(i)
Use the equation in the box to calculate the acceleration of the athlete.
Show clearly how you work out your answer.
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Acceleration = ..............................
(2)
(ii)
Which one of the following is the unit for acceleration?
Draw a ring around your answer.
J/s
m/s
m/s2
Nm
(1)
(iii)
Complete the following sentence.
The velocity of the athlete is the .................................................................... of the
athlete in a given direction.
(1)
(iv)
Complete the graph to show how the velocity of the athlete changes during the first
2 seconds of the race.
(2)
(b)
Many running shoes have a cushioning system. This reduces the impact force on the
athlete as the heel of the running shoe hits the ground.
The bar chart shows the maximum impact force for three different makes of running shoe
used on three different types of surface.
(i)
Which one of the three makes of running shoe, A, B or C, has the best cushioning
system?
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Explain the reason for your answer.
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(3)
(ii)
The data needed to draw the bar chart was obtained using a robotic athlete fitted
with electronic sensors.
Why is this data likely to be more reliable than data obtained using human athletes?
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(1)
(Total 10 marks)
Q21.
(a)
The diagram shows a car travelling at a speed of 12 m/s along a straight road.
(i)
Use the equation in the box to calculate the momentum of the car.
momentum = mass × velocity
Mass of the car = 900 kg
Show clearly how you work out your answer.
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Momentum = .............................. kg m/s
(2)
(ii)
Momentum has direction.
Draw an arrow on the diagram to show the direction of the car’s momentum.
(1)
(b)
The car stops at a set of traffic lights.
How much momentum does the car have when it is stopped at the traffic lights?
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Give a reason for your answer.
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(2)
(Total 5 marks)
Q22.(a)
Complete the sentence.
In a closed system, when two objects collide, the total momentum of the two objects
before the collision is ...................................................................................... the total
momentum of the two objects after the collision.
(1)
(b)
The diagram shows a car before and after the car collides with a stationary van.
The handbrake of the van is not on.
Use the information in the diagram to calculate the velocity, v, in metres per second, with
which the van moves forwards after the collision.
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Velocity = ........................................................ m/s
(4)
(c)
The graph shows the velocity of the car before, during and after the collision.
Use the graph to calculate the distance travelled by the car, in metres, after the collision.
........................................................................................................................
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Distance = ............................................ m
(2)
(d)
The collision causes the car driver to jerk forward.
Explain why wearing a seat belt reduces the risk of the driver being injured in the collision.
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(3)
(Total 10 marks)
Q23.
(a)
(i)
In any collision, the total momentum of the colliding objects is usually conserved.
What is meant by the term ‘momentum is conserved’?
...............................................................................................................
...............................................................................................................
(1)
(ii)
In a collision, momentum is not always conserved.
Why?
...............................................................................................................
...............................................................................................................
(1)
(b)
The diagram shows a car and a van, just before and just after the car collided with the
van.
After collision
Before collision
(i)
Use the information in the diagram and the equation in the box to calculate
thechange in the momentum of the car.
momentum = mass × velocity
Show clearly how you work out your answer and give the unit.
...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................
Change in momentum =..................................................
(3)
(ii)
Use the idea of conservation of momentum to calculate the velocity of the van when
it is pushed forward by the collision.
Show clearly how you work out your answer.
...............................................................................................................
...............................................................................................................
...............................................................................................................
Velocity =.................................................. m/s forward
(2)
(Total 7 marks)
Q24.
(a) The diagram shows three identical go-karts, P, Q and R, travelling at different speeds
along the straight part of an outdoor racetrack.
Which go-kart, P, Q or R, has the greatest momentum?
........................................................................................................................
Give the reason for your answer.
........................................................................................................................
........................................................................................................................
(2)
(b)
The total mass of go-kart Q and the driver is 130 kg.
(i)
Use the equation in the box to calculate the total momentum of go-kart Q and the
driver.
momentum = mass × velocity
Show clearly how you work out your answer.
...............................................................................................................
...............................................................................................................
Momentum = ...........................................
(2)
(ii)
Which of the following is the unit of momentum?
Draw a ring around your answer.
J/s
kg m/s
Nm
(1)
(c)
To race safely at high speed, a go-kart driver must have fast reaction times and the
outdoor racetrack should be dry.
(i)
How would being tired affect a driver’s reaction time?
...............................................................................................................
(1)
(ii)
How would a wet track affect the braking distance of a go-kart?
...............................................................................................................
(1)
(Total 7 marks)
Q25.The arrows in the diagram represent the horizontal forces acting on a motorbike at one moment
in time.
(a)
The mass of the motorbike and rider is 275 kg.
Use the equation in the box to calculate the acceleration of the motorbike at this moment
in time.
resultant force
=
mass
×
acceleration
Show clearly how you work out your answer.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
Acceleration = ............................................................ m/s2
(3)
(b)
A road safety organisation has investigated the causes of motorbike accidents.
The main aim of the investigation was to find out whether there was any evidence that
young, inexperienced riders were more likely to be involved in an accident than older,
experienced riders.
Data obtained by the organisation from a sample of 1800 police files involving motorbike
accidents, is summarised in the table.
Size of
motorbikeengine
Percentage of
allmotorbikes sold
Total number inthe
sample of
1800accident files
up to 125 cc
36
774
126 to 350 cc
7
126
351 to 500 cc
7
162
over 500 cc
50
738
Most of the motorbikes with engines up to 125 cc were ridden by young people.The
motorbikes with engines over 500 cc were ridden by older, more experienced riders.
(i)
In terms of the main aim of the investigation, is this data valid?
Draw a ring around your answer.
NO
YES
Explain the reason for your answer.
...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................
(2)
(ii)
The organisation concluded that:
“Young, inexperienced riders are more likely to be involved in a motorbike accident
than older, experienced riders”.
Explain how the data supports this conclusion.
...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................
(2)
(c)
Of particular concern to motorbike riders is the design of steel crash barriers. Riders
falling off and sliding at high speed into a steel support post are often seriously injured.
One way to reduce the risk of serious injury is to cover the post in a thick layer of high
impact polyurethane foam.
(i)
Use the ideas of momentum to explain how the layer of foam reduces the risk of
serious injury to a motorbike rider sliding at high speed into the support post.
...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................
(3)
(ii)
Crash barrier tests use dummies that collide at 17 m/s with the barrier. Each test
costs about £12 000. New safety devices for crash barriers are tested many times to
make sure that they will improve safety.
Do you think that the cost of developing the new safety devices is justified?
Draw a ring around your answer.
NO
YES
Give a reason for your answer.
...............................................................................................................
...............................................................................................................
(1)
(Total 11 marks)
Q26.
Motorway accidents have many causes.
(a)
Which one of the following is most likely to increase the chance of a car being in an
accident?
Tick (
) the box next to your answer.
The car has just had new tyres fitted.
The driver has been drinking alcohol.
A road surface in dry conditions
Give a reason for your answer.
........................................................................................................................
........................................................................................................................
(2)
(b)
The diagram shows three designs of motorway crash barriers.
Steel sheets
Steel ‘ropes’
Solid concrete
Before a new design of barrier is used, it must be tested.
A car of mass 1500 kg is driven at 30 m/s to hit the barrier at an angle of 20 degrees.
This barrier must slow the car down and must not break.
Explain why the mass of the car, the speed of the car and the angle at which the car hits
the barrier must be the same in every test.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(c)
A group of scientists has suggested that new designs of crash barriers should be first
tested using computer simulations.
Which two statements give sensible reasons for testing new barrier designs using a
computer simulation?
Put a tick (
) in the box next to each of your answers.
The design of the barrier can be changed easily.
Data for different conditions can be obtained quickly.
Simulations are more realistic than using cars and barriers.
(1)
(Total 5 marks)
Q27.
(a)
(i)
The diagram shows three vehicles travelling along a straight road at 14 m/s.
Which vehicle has the greatest momentum?
............................................................
Give the reason for your answer.
...............................................................................................................
...............................................................................................................
...............................................................................................................
(2)
(ii)
Use the equation in the box to calculate the momentum of the motorbike when it
travels at 14 m/s.
momentum
=
mass
×
velocity
Show clearly how you work out your answer.
...............................................................................................................
...............................................................................................................
Momentum = ............................................................kg m/s
(2)
(b)
The motorbike follows the lorry for a short time, and then accelerates to overtake both the
lorry and van.
(i)
Complete the following sentence by drawing a ring around the correct line in the
box.
When the motorbike starts to overtake, the kinetic energy
decreases.
of the motorbike
stays the same.
increases.
(1)
(ii)
Give a reason for your answer to part (b)(i).
...............................................................................................................
...............................................................................................................
(1)
(iii)
The graph shows the velocity of the motorbike up to the time when it starts to
accelerate. The motorbike accelerates constantly, going from a speed of 14 m/s to a
speed of 20 m/s in a time of 2 seconds. The motorbike then stays at 20 m/s.
Complete the graph to show the motion of the motorbike over the next 4 seconds.
(3)
(Total 9 marks)
Q28.
(a)
Complete the following sentence.
The momentum of a moving object has a magnitude, in kg m/s,
and a .................................................. .
(1)
(b)
A car being driven at 9.0 m/s collides with the back of a stationary lorry.The car slows
down and stops in 0.20 seconds. The total mass of the car and driver is 1200 kg.
Use the equations in the box to calculate the average force exerted by the lorry on the car
during the collision.
Show clearly how you work out your answer.
........................................................................................................................
........................................................................................................................
Force = .................................................. N
(2)
(c)
Within 0.04 s of the car hitting the back of the lorry, the car driver's airbag inflates.
The airbag deflates when it is hit by the driver’s head.
Use the idea of momentum to explain why the airbag reduces the risk of the drive
sustaining a serious head injury.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(Total 6 marks)
Q29.
(a) A van has a mass of 3200 kg. The diagram shows the van just before and just after it
collides with the back of a car.
After collision
Before collision
Just before the collision, the van was moving at 5 m/s and the car was stationary.
(i)
Use the equation in the box to calculate the momentum of the van just before the
collision.
momentum
=
mass
×
velocity
Show clearly how you work out your answer.
...............................................................................................................
...............................................................................................................
Momentum = .............................. kg m/s
(2)
(ii)
The collision makes the van and car join together.
What is the total momentum of the van and the car just after the collision?
Momentum = .............................. kg m/s
(1)
(iii)
Complete the following sentence by drawing a ring around the correct line in the box.
more than
The momentum of the car before the collision is
the same
as
less than
the
momentum of the car after the collision.
(1)
(b)
A seat belt is one of the safety features of a car.
In a collision, wearing a seat belt reduces the risk of injury.
Use words or phrases from the box to complete the following sentences.
decreases
stays the same
increases
In a collision, the seat belt stretches. The time it takes for the person held by the seat belt
to lose momentum compared to a person not wearing a seat belt,
.................................................................................................... .
The force on the person’s body ............................................................................. and so
reduces the risk of injury.
(2)
(Total 6 marks)
Q30.(a)
The picture shows two teenagers riding identical skateboards.The skateboards are moving
at the same speed and the teenagers have the same mass.
Why do the teenagers not have the same momentum?
........................................................................................................................
........................................................................................................................
(1)
(b)
One of the skateboards slows down and stops. The teenager then jumps off the
skateboard, causing it to recoil and move in the opposite direction.
The momentum of the teenager and skateboard is conserved.
(i)
What is meant by ‘momentum being conserved’?
...............................................................................................................
...............................................................................................................
(1)
(ii)
The teenager, of mass 55 kg, jumps off the skateboard at 0.4 m/s causing the
skateboard to recoil at 10 m/s.
Use the equation in the box to calculate the mass of the skateboard.
momentum
=
mass
×
velocity
...............................................................................................................
...............................................................................................................
...............................................................................................................
Mass = ............................................................ kg
(3)
(c)
Once the skateboard starts to recoil, it soon slows down and its kinetic energy decreases.
Explain why.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 7 marks)
Q31.
The picture shows three skateboarders, A, B and C.
Skateboarder A is not moving.Skateboarder B is moving towards the ramp at a constant
speed.Skateboarder C is moving on the ramp at a constant speed.
(a)
The skateboarders have different amounts of kinetic energy.
Which two factors affect the kinetic energy of the skateboarders?
Put a tick (
) in the box next to your answer.
direction and mass
mass and speed
speed and direction
(1)
(b)
The skateboarders also have different amounts of momentum.
(i)
Which one of the skateboarders has the smallest amount of momentum?
Draw a ring around your answer.
A
B
C
Give a reason for your answer.
...............................................................................................................
...............................................................................................................
(2)
(ii)
Skateboarder B has a mass of 55 kg.
Use the equation in the box to calculate the momentum of skateboarder B when
moving at 4 m/s.
momentum
=
mass
×
velocity
Show clearly how you work out your answer.
...............................................................................................................
...............................................................................................................
Momentum = .................................................. kg m/s
(2)
(Total 5 marks)
Q32.
The picture shows players in a cricket match.
(a)
A fast bowler bowls the ball at 35 m/s. The ball has a mass of 0.16 kg.
Use the equation in the box to calculate the kinetic energy of the cricket ball as it leaves
the bowler’s hand.
kinetic energy =
× mass × speed2
Show clearly how you work out your answer.
........................................................................................................................
........................................................................................................................
........................................................................................................................
Kinetic energy = ............................................................ J
(2)
(b)
When the ball reaches the batsman it is travelling at 30 m/s. The batsman strikes the ball
which moves off at 30 m/s in the opposite direction.
(i)
Use the equation in the box to calculate the change in momentum of the ball.
momentum
=
mass
×
velocity
Show clearly how you work out your answer.
...............................................................................................................
...............................................................................................................
Change in momentum = ........................................................... kg m/s
(2)
(ii)
The ball is in contact with the bat for 0.001 s.
Use the equation in the box to calculate the force exerted by the bat on the ball.
Show clearly how you work out your answer.
...............................................................................................................
...............................................................................................................
Force = ............................................................ N
(1)
(c)
A fielder, as he catches a cricket ball, pulls his hands backwards.
Explain why this action reduces the force on his hands.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 7 marks)
Q33.
(a) A car is being driven along a straight road. The diagrams, A, B and C, show the
horizontal forces acting on the moving car at three different points along the road.
Describe the motion of the car at each of the points, A, B and C.
(3)
(b)
The diagram below shows the stopping distance for a family car, in good condition, driven
at 22 m/s on a dry road. The stopping distance has two parts.
(i)
Complete the diagram below by adding an appropriate label to the second part of
the stopping distance.
.............................................................
.............................................................
(1)
(ii)
State one factor that changes both the first part and the second part of the stopping
distance.
...............................................................................................................
(1)
(c)
The front crumple zone of a car is tested at a road traffic laboratory. This is done by using
a remote control device to drive the car into a strong barrier. Electronic sensors are
attached to the dummy inside the car.
(i)
At the point of collision, the car exerts a force of 5000 N on the barrier.
State the size and direction of the force exerted by the barrier on the car.
...............................................................................................................
...............................................................................................................
(1)
(ii)
Suggest why the dummy is fitted with electronic sensors.
...............................................................................................................
...............................................................................................................
(1)
(iii)
The graph shows how the velocity of the car changes during the test.
Use the graph to calculate the acceleration of the car just before the collision with
the barrier.
Show clearly how you work out your answer, including how you use the graph, and
give the unit.
...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................
Acceleration = ............................................................
(3)
(Total 10 marks)
Q34.
(a)
The diagrams, A, B and C, show the horizontal forces acting on a moving car.
Draw a line to link each diagram to the description of the car’s motion at the moment when
the forces act.
Draw only three lines.
stationary
A
constant speed
B
slowing down
C
accelerating
forwards
(3)
(b)
The front crumple zone of a car is tested at a road traffic laboratory. This is done by using
a remote control device to drive the car into a strong barrier. Electronic sensors are
attached to a dummy inside the car.
(i)
Draw an arrow in Box 1 to show the direction of the force that the car exerts on the
barrier.
(1)
(ii)
Draw an arrow in Box 2 to show the direction of the force that the barrier exerts on
the car.
(1)
(iii)
Complete the following by drawing a ring around the correct line in the box.
The car exerts a force of 5000 N on the barrier. The barrier does not move. The
force
more
than
exerted by the barrier on the car will be
equal to
5000 N.
less than
(1)
(iv)
Which one of the following gives the most likely reason for attaching electronic
sensors to the dummy?
Put a tick (
) in the box next to your answer.
To measure the speed of the car just before the impact.
To measure the forces exerted on the dummy during the impact.
To measure the distance the car travels during the impact.
(1)
(Total 7 marks)
Q35.
(a)
The diagrams, A, B and C, show the horizontal forces acting on a moving car.
Draw a line to link each diagram to the description of the car’s motion at the moment when
the forces act.
Draw only three lines.
stationary
A
constant speed
B
slowing down
C
accelerating
forwards
(3)
(b)
The front crumple zone of a car is tested at a road traffic laboratory. This is done by using
a remote control device to drive the car into a strong barrier. Electronic sensors are
attached to a dummy inside the car.
(i)
Draw an arrow in Box 1 to show the direction of the force that the car exerts on the
barrier.
(1)
(ii)
Draw an arrow in Box 2 to show the direction of the force that the barrier exerts on
the car.
(1)
(iii)
Complete the following by drawing a ring around the correct line in the box.
The car exerts a force of 5000 N on the barrier. The barrier does not move. The
force
more
than
exerted by the barrier on the car will be
equal to
5000 N.
less than
(1)
(iv)
Which one of the following gives the most likely reason for attaching electronic
sensors to the dummy?
Put a tick (
) in the box next to your answer.
To measure the speed of the car just before the impact.
To measure the forces exerted on the dummy during the impact.
To measure the distance the car travels during the impact.
(1)
(Total 7 marks)
##
(a)
ideas that greater speed means more kinetic energy
gains 1 mark
but any evidence of the formula ½ mv2
but making the case that kinetic energy depends on the speed squared
gains 3 marks
or that 22 = 4
3
(b)
(i)
any evidence of concept of momentum or mass × speed(or velocity) in words or figures
e.g. 9.5 × 20 or 0.5 × 40
gains 1 mark
but correct values for momentum of lorry and cari.e. 190 and 20 [ignore units]
gains 2 marks
but initial momentum correctly calculated170 or 190 – 20
gains 3 marks
THEN
evidence when calculating final speed of
idea that momentum is conserved
use of combined mass
each gain 1 mark
but
17 [or 0.1 × figure for initial momentum]
(NB direction not required)
gains 3 marks
6
(ii)
kinetic energy is lost
for 1 mark
[credit (some kinetic) energy transferred as heat/sound]
[NB Accept only answers in terms of energy as required by the question]
1
[10]
M2.
(a)
product of mass and velocity
1
(b)
(i)
4kg or 4000g
1
(ii)
M = 8kgm/s or Ns
for 3 marks
else M = 8
for 2 marks
else M – mv or 4 × 2
for 1 mark
3
(iii)
8 kgm/s (watch e.c.f.)
1
(iv)
v = 400
for 3 marks
else v = 8/0.02
for 2 marks
else M – mv, v – M/m or 8 = 0.02v
for 1 mark
3
(v)
ke = 8
for 3 marks
else ke = 1/2 (4 × 22)
for 2 marks
else ke = 1/2 (mv2)
for 1 mark
3
(vi)
transferred to heat and sound
or does work against wood/pushing wood aside/deforming bullet
1
[13]
M3.
(a) Throughout the question the equation M = mv is credited once only.
This is the first time it appears. The mark scheme below assumes
it will appear in (i).
(i)
M = mv m × v sufficient not m × s, mass × speed
= 1500 × 8
= 12 000
(see marking of calculations)
3
(ii)
M = mv
M = 2000 × 1 = 2000
(see marking of calculations)
2
(iii)
must be sum of (i) and (ii) 14 000
for 1 mark
1
(b)
total mass = 3500momentum = 14 000 (conserved)M = mv or v = 14 000/3500v = 4m/s
5
(c)
(i)
it reduces
for 1 mark
1
(ii)
ke to sound/heat
for 1 mark
1
(iii)
change smaller
for 1 mark
1
[14]
M4.
(a)
mass and velocity/speed multiplied
for 1 mark each
2
(b)
total momentum before and after collision are the same
for 1 mark each
2
(c)
(i)
MAUA + MBUB = (MA + MB)v
2 × 6 = (2 + 1)v
v=4
m/s
for 1 mark each
4
(ii)
1/2 mv2 (before) – 1/2 mv2 (after) 1/2 2.36 – 1/2 3.16 = 12
J
for 1 mark each
4
[12]
M5.
(a)
(i)
6
for 1 mark
1
(ii)
6
for 1 mark
1
(iii)
1.5
for 1 mark
1
(iv)
4.5
for 1 mark
1
(v)
3
for 1 mark
1
(b)
initial ke = 12J;
final ke = 0.75J + 6.75J;
energy loss = 4.5J
for 1 mark each
(If wrong; any correct ke value gains 1 mark; maximum of 2
path through calculation clear and correct gains 1 mark)
(ignore either ball – max 1 mark)
3
[8]
M6.
(a)
the snow
1
smallest mass
do not accept it is not moving
accept weight for mass
accept it’s the lightest
1
(b)
(i)
decrease
1
velocity reducing
accept speed for velocity
accept it is stopping
do not accept the brakes are on
accept car is decelerating
1
(ii)
forwards
1
direction of momentum does not change or the car stops and snow does not
dependent on forwards given
accept answers given in terms of Newton’s second or first law of
motion
accept momentum of snow
do not accept the snow still has momentum
1
(c)
Ns
1
[7]
M7.
(a)
(i)
direction indicated
accept to right or + or – or arrow drawn on diagram
1
300
1
kg m/s or Ns
1
(ii)
300 (kg m/s)
1
(iii)
there is no change in the total KE
or total KE is constant
1
(b)
momentum of person towards jetty = momentum of boat away from jetty
or total momentum is constant so as person goes one way boat goes the other
1 mark is for the idea of momentum conservation
1 is for direction
2
(c)
time of collision increases
do not accept momentum is conserved
1
so a smaller force is exerted
do not accept designed to absorb energy or momentum
1
to produce the same change of momentum or impulse force
do not accept cushions fall
1
[10]
M8.
(a)
(i)
zero
accept nothing
1
speed is zero
accept not moving
1
(ii)
A
1
largest mass or weight
accept heaviest luggage
do not accept largest luggage
1
(iii)
momentum does change
accept yes
1
direction is changing
accept velocity is changing
do not accept answers in terms of
speed changing
1
(iv)
kg m/s
1
[7]
M9.
(a)
Total momentum (of a system of bodies) remains constant
accept momentum before (a collision) = momentum after (a
collision)
1
Provided no external force acts
1
(b)
(i)
rotate the compressor
1
(ii)
•
fuel is mixed with the air and ignited
•
causing an increase in the pressure
or temperature or speed of the gases
accept air out faster than air in
accept gases have momentum or
•
force backwards
•
exhaust gases have momentum
(backwards) or force (backwards)
if the answer is in terms of force then this third point must be
scored before the fourth can be credited
•
engine or aircraft has (equal) momentum forwards or force forwards
4
(c)
m = 350
answer 0.35 one mark only
allow one mark if 105 000 or 475-175 or 300 have been used
2
[9]
M10.
(a)
(i)
either
the momentum in a particular direction after (the collision) is the same as the
momentum in that direction before (the collision)
accept ‘momentum before equals momentum after’ for 1 mark
or total momentum after (the collision) equals the total momentum before
(the collision) (2)
accept ‘momentum before equals momentum after’ for 1 mark
2
(ii)
explosion(s)
or (action of a) rocket (motor(s))
or (action of a) jet (engine)
or firing a gun
accept any other activity in which things move apart as a result of
the release of internal energy eg throwing a ball
1
(iii)
momentum = mass
velocity or any correctly transposed version
accept momentum = mass
speedaccept p = mvdo not accept
momentum = msor M = mv
1
(iv)
0.8
if answer 0.8 not given, any two for (1) each:
momentum of X = 0.2
1.2
= momentum of X and Y after impact
= 0.3
v or = (0.1 + 0.2)
v
3
m/s
1
to the right
1
(v)
any one from:
conservation of momentum (applies)
no external forces
do not accept just ‘no (other) forces act’
friction is negligible / insignificant
no friction
no air resistance
1
(b)
force = (change in) momentum ÷ time
or any correctly transposed version
1
4000 or 4 kilonewtons
dependent on correct or no equation
force = 5 ÷ 0.00125 gains 1 mark
2
[13]
M11.
(a)
(i)
momentum = mass × velocity
accept … × speed or any transposed version
1
(ii)
11.2 to 11.3
0.75 × 15 for 1 mark
2
kg m/s down(wards) or Ns down(ward)
n.b. both unit and direction required for this mark
1
(iii)
11.2 to 11.3
accept same numerical answer as part (a)(ii)
accept answer without any unit or with the same unit as in part
(a)(ii), even if incorrect, but any other unit cancels the mark
1
(iv)
force =
accept transposed version
1
(v)
112 to 113 or numerical value from (a)(ii) × 10
11.25 ÷ 0.1 or (a)(ii) ÷ 0.1 for 1 mark
2
newton(s)
or N
accept Newton(s)
do not credit ‘Ns’ or n
1
(b)
(the user will experience a) large change in momentum
do not credit just ‘… momentum changes’
1
(but) seat belt increases the time for this to occur orseat belt stops you hitting something
which would stop you quickly
do not credit just ‘… stops you hitting the windscreen etc.’
1
(so) the force on the user is less(*)
1
(so) less chance of (serious / fatal) injury(*)
(*) depends on previous response re momentum or continued
movement
1
[13]
M12.
(i)
momentum (change in) = mass × velocity (change in)
accept ... speed
1
(ii)
9000
1500 × 6 for 1 mark but not from incorrect equation
2
kilogram metre(s) per second or kg m/s
1
(iii)
either 7.5 (m/s)
or change in momentum of car B change in momentum of car A (1)
9000 = 1200 × v (1)
or v = 9000 ÷ 1200 (1)
or error carried forward from part (ii)
examples
5 (m/s) if 6000 offered in (ii) (3)
12.5(m/s) if 15000 offered in (ii)
(3)
3
[7]
M13.
(a)
4 (m/s)
1 mark for correct transformation of either equation1 mark for
correct substitution with or without transformation1 mark for correct
use of 0.6N
max score of 2 if answer is incorrect
3
(b)
greater change in momentum
or greater mass of air (each second)
or increase in velocity of air
accept speed for velocity
force upwards increased
lift force is increased
do not accept upthrust
1
or force up greater than force down
accept weight for force down
1
(c)
•
increase the time to stop
1
•
decrease rate of change in momentum or same momentum change
accept reduced deceleration/ acceleration
1
•
reducing the force on the toy
do not accept answers in terms of the impact/ force being
absorbed
do not accept answers in terms of energy transfer
do not credit impact is reduced
1
[8]
M14.
(a)
(i)
0.6
allow 1 mark for correct substitution
2
newtons
accept N
do not accept n
accept Newtons
1
(ii)
the same as
1
(b)
(i)
changed velocity
accept increased/ decreased for change
accept speed for velocity
accept change direction
accept getting faster/ slower
accept start/ stop moving
accept correct equation in terms of change in speed or change in
velocity
1
(ii)
down(wards)
accept towards the ground
accept ↓
do not accept south
1
(iii)
increase
velocity is increasing
can only credit second mark if answer is increase
or it is accelerating
accept speed for velocity
accept is moving faster
1
accept an answer in terms of resultant force downwards
mention of weight/ mass increasing negates second mark
1
[8]
M15.
(a)
(i)
velocity includes direction
accept velocity is a vector
1
(ii)
64
allow 1 mark for obtaining values of 16 and 4 from the graph
or marking correct area or correct attempt to calculate an area
2
(iii)
any two from:
•
velocity zero from 0 to 4 seconds
•
increasing in 0.2 s (or very rapidly) to 8 m/s
•
decreasing to zero over the next 8 seconds
2
(iv)
momentum before does not equal momentum after
ignore reference to energy
or total momentum changes
or an external force was applied
1
(b)
to reduce the momentum of the driver
1
a smaller (constant) force would be needed
do not accept reduces the impact / impulse on the driver
1
[8]
M16.
(a)
(i)
mass
do not accept weight
1
speed
accept velocity
answers can be in either order
1
(ii)
zero
accept nothing
1
(b)
(i)
100
allow 1 mark for correct substitution of data
2
(ii)
conserved
1
[6]
M17.
(a)
(i)
210
allow 1 mark for correct substitution i.e. 35 × 6
2
kg m/s or Ns
do not accept n for N
accept 210 000g m/s for 3 marks
1
(ii)
840
if answer given is not 840 accept their (a)(i) in kg m/s ÷ 0.25
correctly calculated for both marks
allow 1 mark for correct substitution i.e. 210 ÷ 0.25 or their
(a)(i) ÷0.25
2
(b)
increases the time to stop
accept increases impact time
do not accept any references to slowing down time
1
decreases rate of change in momentum
accept reduces acceleration/deceleration
reduces momentum is insufficient
1
reduces the force (on the child)
1
(c)
any two from:
•
insufficient range of tests/thicknesses for required cfh
accept need data for thicknesses above 80 mm/ cfh 2.7 m
not enough tests is insufficient
•
(seems to be) some anomalous data
•
(repeats) needed to improve reliability (of data)
accept data/ results are unreliable
do not accept maybe systematic/random error
do not accept reference to precision
•
need to test greater range/variety of dummies
accept children for dummies
accept specific factor such as weight/height/size
2
(d)
Tyres do not need to be dumped/burned/ less land-fill/ saves on raw
materials
accept less waste
do not accept recycling on its own
1
[11]
M18.
(a)
(i)
the thicker the tile, the greater the(fall) height
accept the higher (the fall) the thicker the tile
accept there is a positive correlation
do not accept they are proportional
1
(ii)
60 (mm)
accept any number or range between 60 and 85 inclusiveif units
are given must match range
1
(minimum thickness) needed to reduce risk of injury
reason must match thickness choicedo not accept to keep child
safe
accept an answer in terms of – the thicker the tile, the less chance
there is of a serious injury if the answer given is greater than 60
accept answers in terms of use of graph e.g. the graph shows that
for a 2m fall a thickness of 60 mm is needed
minimum level answer’ the graph shows that’s what’s needed’
accept only if 60 is the answer
1
(b)
(i)
the time taken (to stop)
1
(ii)
(the) force (on)
1
[5]
M19.
(a)
Y
accept the one in the middle
accept 90
1
has the biggest mass
reason does not score if X or Z is chosen
accept weight for mass
accept weighs the most
accept they are the heaviest
accept has a larger mass
do not accept weighs 90kg’s on its own
biggest/larger on its own is not sufficient
1
(b)
increases
1
[3]
M20.
(a)
(i)
4.5
allow 1 mark for correct substitution i.e. 9 ÷ 2
2
(ii)
m/s2
accept answer given in (a)(i) if not contradicted here
1
(iii)
speed
1
(iv)
straight line from the origin passing through (2s, 9m/s)
allow 1 mark for straight line from the origin passing through to t =
2 seconds
allow 1 mark for an attempt to draw a straight line from the origin
passing through (2,9)
allow 1 mark for a minimum of 3 points plotted with no line
provided if joined up would give correct answer. Points must
include(0,0) and (2,9)
2
(b)
(i)
B
if A or C given scores 0 marks in total
1
smallest (impact) force
1
on all/ every/ any surfaces
these marks are awarded for comparative answers
1
(ii)
(conditions) can be repeated
or
difficult to measure forces with human athletes
accept answers in terms of variations in human athletes e.g.
athletes may have different weights area / size of feet may be
different difficult to measure forces athletes run at different speeds
accept any answer that states or implies that with humans the
conditions needed to repeat tests may not be constant
e.g.
athletes unable to maintain constant speed during tests (or during
repeat tests)
do not accept the robots are more accurate
removes human error is insufficient
fair test is insufficient
1
[10]
M21.
(a)
(i)
10800
allow 1 mark for correct substitution i.e. 900 × 12
2
(ii)
arrow pointing towards the left
allow anywhere on the diagram or at bottom of the page
1
(b)
zero
accept 0 / none / nothing
1
velocity is zero
accept speed for velocity
accept stopped / not moving
accept a calculation i.e. 900 × 0 = 0
1
[5]
M22.(a)
equal to
or
the same as
1
(b)
momentum of car before collision = 1200 × 10 = 12 000
1
momentum after collision = 12 000
1
or
momentum is conserved equating
ie 12 000 = 1200 × 2 + 3200v
1
3 (m/s)
correct answer with or without working gains 4 marks
1
(c)
correct area used from the graph
1
1.5 (m)
correct answer with or without working gains 2 marks
1
(d)
the time taken for the driver to stop (moving forward) increases
1
which decreases the rate of change in momentum
accept reduces deceleration
1
so the force on the driver is reduced
1
[10]
M23.
(a)
(i) momentum before = momentum after
or
(total) momentum stays the same
accept no momentum is lost
accept no momentum is gained
1
(ii)
an external force acts (on the colliding objects)
accept colliding objects are not isolated
1
(b)
(i)
9600
allow 1 mark for correct calculation of momentum before or after
ie 12000 or 2400
or
correct substitution using change in velocity = 8 m/s
ie 1200 × 8
2
kg m/s
this may be given in words rather than symbols
or
Ns
1
(ii)
3 or their (b)(i) ÷ 3200 correctly calculated
allow 1 mark for stating momentum before = momentum after
or
clear attempt to use conservation of momentum
2
[7]
M24.
(a)
R
reason cannot score if R is not chosen
1
has the greatest speed / velocity
accept it is going at 28 m/s
answer should be comparative
1
(b)
(i)
3250
allow 1 mark for correct substitution of 130 and 25
ie 130 × 25
accept 2600 or 3640 for 1 mark
2
(ii)
kg m/s
accept answer given in (b)(i) if no answer given here
1
(c)
(i)
increase it
accept make it slower
accept slow it down
accept make it longer
accept (reactions) would be slower
do not accept if the answer clearly refers to distance
comparative answers expected
1
(ii)
increase it
accept make it longer
do not accept if the answer clearly refers to time
comparative answers expected
1
[7]
M25.
(a)
4.2
2 marks for correct substitution and transformation, ie 1155/275
allow 1 mark for correct resultant force with a subsequent incorrect
method, ie 1155
allow 1 mark for an incorrect resultant force with a subsequent
correct method,
eg answers of 7.27 or 10.34 gain 1 mark
3
(b)
(i)
YES
marks are for the explanation
any two from:
•
data (from police files) can be trusted
•
data answers the question asked
allow a conclusion can be made from the data
•
large sample used
NO
any two from:
•
the sample is not representative
•
the sample size is too small
•
accident files do not indicate age / experience of riders
an answer YES and NO can score 1 mark from each set of mark
points
2
(ii)
more accidents with motorbikes up to 125 cc
accept for 2 marks an answer in terms of number of under 125 cc
to accidents ratio compared correctly with number of over 500 cc
to accidents ratio
1
even though there are fewer of these bikes than bikes over 500 cc
1
(c)
(i)
increases the time taken to stop
accept increases collision time
1
decreases rate of change in momentum
accept reduces acceleration / deceleration
accept
reduces momentum is insufficient
1
reduces the force (on the rider)
1
(ii)
YES
any sensible reason, eg:
the mark is for the reason
•
cannot put a price on life / injury
accept may save lives
•
fewer (serious) injuries
accept reduces risk of injury
•
reduces cost of health care / compensation
NO
any sensible suggestion, eg:
•
money better spent on …
needs to be specific
•
total number of riders involved is small
1
[11]
M26.
(a)
The driver has been drinking alcohol.
reason only scores if this box is ticked
1
driver's reaction time increases
accept slower reactions
accept slower reaction time
or
thinking distance / stopping distance increases
do not accept braking distance increases
or
driver less alert
accept driver may fall asleep / be tired
1
(b)
they are all variables that could affect outcome / results
accept specific effect of changing one of the variables
accept to make the test valid
ignore reliable
1
so data / barriers can be compared
accept to see which is / works best / safest
do not accept fair test on its own
1
(c)
ticks in both the top and middle boxes
1
[5]
M27.
(a)
(i)
lorry
reason only scores if lorry chosen
1
greatest mass
accept weight for mass
accept heaviest
accept correct calculations for all 3 vehicles
the biggest is insufficient
1
(ii)
2450
allow 1 mark for correct substitution
ie 175 × 14
2
(b)
(i)
increases
accept any clear indication of the correct answer
1
(ii)
speed increases
accept velocity for speed
accept gets faster
do not accept it accelerates on its own
moves more is insufficient
1
(iii)
straight line going to 6, 20
allow 1 mark for a curve going to 6,20
or a straight line diagonally upwards but missing 6,20
2
horizontal line from 6,20 to 8,20
allow a horizontal line from where their diagonal meets 20m/s to
8,20
1
[9]
M28.
(a)
direction
1
(b)
54 000
allow 1 mark for calculating and identifying momentum as 10 800
or
allow 1 mark for correct substitution into second equation
ie
2
(c)
increases the time taken (for head) to stop
accept increases impact time
do not accept reference to slowing down time unless qualified
1
decreases rate of change in momentum
accept reduces acceleration / deceleration
accept increases the time taken to reduce momentum to zero is
worth 2 marks
reduces momentum is insufficient
1
reduces the force (on the head)
1
[6]
M29.
(a)
(i)
16 000
allow 1 mark for correct substitution ie 3200 × 5
2
(ii)
16 000 or their (a)(i)
1
(iii)
less than
1
(b)
increases
1
decreases
correct order only
1
[6]
M30.
(a)
(moving in) different / opposite directions
accept one has positive momentum the other negative momentum
accept they have different velocities
1
(b)
(i)
momentum before = momentum afteror(total) momentum stays the same
accept no momentum is lost
accept no momentum is gained
1
(ii)
2.2
allow 1 mark for calculation of teenagers’ momentum as
22 (kgm/s) and
allow 1 mark for correct statement, eg momentum
before = momentum after
or
allow 2 marks for a numerical expression of above, eg
55 × 0.4 = m × 10
or 0 = (55 × 0.4) + (m × (-10))
3
(c)
any two from:
•
work is done
•
(against) friction
any reference to increasing friction negates this marking point
•
(transforming) (kinetic) energy into heat
2
[7]
M31.
(a)
mass and speed
1
(b)
(i)
A
reason cannot score if B or C chosen
1
velocity = 0 (m/s)
accept speed for velocity
accept not moving
accept lowest velocity / speed
1
(ii)
220
allow 1 mark for correct substitution,
ie 55 × 4 provided no subsequent step shown
2
[5]
M32.
(a)
98
allow 1 mark for correct substitution
ie ½ × 0.16 × 35 × 35 provided no subsequent step shown
an answer of 98 000 scores 0
2
(b)
(i)
9.6
allow 1 mark for (change in velocity =) 60
ignore negative sign
2
(ii)
9600
ignore negative sign
or
their (b)(i) ÷ 0.001 correctly calculated, unless (b) (i) equals 0
1
(c)
increases the time
1
to reduce/change momentum (to zero)
only scores if 1st mark scored
decreases rate of change of momentum scores both marks
provided there are no contradictions
accept decreased acceleration/deceleration
equations on their own are insufficient
1
[7]
M33.
(a)
A constant speed / velocity
accept steady pace
do not accept terminal velocity
do not accept stationary
1
B acceleration
accept speeding up
1
C deceleration
accept slowing down
accept accelerating backwards
accept accelerating in reverse
do not accept decelerating backwards
1
(b)
(i)
the distance the car travels under the braking force
accept braking distance
1
(ii)
speed/velocity/momentum
1
(c)
(i)
5000 (N) to the left
both required
accept 5000(N) with the direction indicated by an arrow drawn
pointing to the left
accept 5000(N) in the opposite direction to the force of the car (on
the barrier)
accept 5000(N) towards the car
1
(ii)
to measure/detect forces exerted (on dummy / driver during the collision)
1
(iii)
4
allow 1 mark for showing a triangle drawn on the straight part of
the graph
or correct use of two pairs of coordinates
2
m/s2
do not accept mps2
1
[10]
M34.(a)
3 lines drawnall correctallow 1 mark for each correct lineif two or more lines are drawn
from any diagram then all these lines are incorrect
3
(b)
(i)
horizontal arrow to the right
judge by eye
accept an arrow drawn outside the box if it is labelled correctly
1
(ii)
horizontal arrow to the left
judge by eye
accept an arrow drawn outside the box if it is labelled correctly
1
(iii)
equal to
1
(iv)
to measure the forces exerted on the dummy during the impact
1
[7]
M35.(a)
3 lines drawnall correctallow 1 mark for each correct lineif two or more lines are drawn
from any diagram then all these lines are incorrect
3
(b)
(i)
horizontal arrow to the right
judge by eye
accept an arrow drawn outside the box if it is labelled correctly
1
(ii)
horizontal arrow to the left
judge by eye
accept an arrow drawn outside the box if it is labelled correctly
1
(iii)
equal to
1
(iv)
to measure the forces exerted on the dummy during the impact
1
[7]
E1.
In (a) few candidates used the formula ½mv2 to answer this question.
In (b)(i) many candidates realised the need to use the idea of momentum in this question
(though some tried to answer using the formula or kinetic energy); fewer correctly calculated the
separate moments of the moving vehicles and fewer still combined these correctly (a common
error being to add them rather than subtract them). Most of the candidates who obtained a
numerical answer for the total initial momentum were able to calculate a final combined speed
consistent with their earlier figure.
In (ii) the idea of a loss of kinetic energy in an inelastic collision (and/or the transfer of kinetic
energy e.g. as heat and sound) was seldom stated.
E2.
E3.
This was not an easy topic but the majority of candidates gained marks in many sections of
the question.
(a)
This was intended as an easy introduction to the question. Very many candidates who
clearly knew momentum was mass x velocity failed to say so in response to this Question
and so failed to gain the mark.
(b)
In (i)few candidates failed to gain the mark. In (ii)the vast majority correctly calculated the
momentum, and then in part (iii)repeated their answer to gain that mark. It was in part
(iv)that the weaker candidates began to run into trouble mainly by using a mass of 4 kg
and working back to a velocity of 2 m/s. A number of candidates turned the Question on
its head at this point; they took the 1600 joules given in part (vi)and used a kinetic energy
calculation to find the velocity. They were awarded all three marks. In (v)many candidates
quoted the kinetic energy equation and went on to calculate the kinetic energy
successfully. Part (vi)presented little trouble to the candidates with energy losses as heat
and sound being common.
Part (a) was generally very well answered with very many candidates gaining full marks.
When working was shown some candidates used momentum as mass times speed rather than
times velocity.
Part (b) proved to be more difficult. The more able candidates gave 14 000/3500 = 4m/s to very
quickly gain the five marks. Most other candidates made some creditable start to the problem to
gain part marks.
In (c)(i) most candidates correctly answered that the kinetic energy would be reduced. In (ii)
many candidates gave a correct energy transfer, the common answer being kinetic energy to
sound. However a surprising number of candidates did not refer to an energy transfer, only
mentioning the outcome of the transfer. Answers like “sound was given off” were not
uncommon. In part (iii) a number of candidates did not answer the question which was
concerned with the change of kinetic energy, instead they referred to the total kinetic energy
after the collision being greater. Such answers were not credited with the mark.
E4.
In part (a) the vast majority of candidates successfully gained both marks for multiplying
mass by velocity. Although there were many correct answers to part (b) some candidates lost
marks for referring to the momentum of ‘an object’ being the same before and after a collision. A
very few answered in terms of the energy before and after the collision and so failed to gain
marks. In part (c) very many candidates scored all the marks with correct calculations. There
were few part correct answers, those who did not score marks generally lost all the marks
through lack of knowledge of the principle of conservation of momentum. A few getting part (i)
wrong nevertheless went on to gain full marks in part (ii) by correctly using the incorrect data
generated in part (i).
E5.
The calculations on momentum were well answered by many candidates, a fair number of
whom went on to complete the kinetic energy calculations in part (b).
E6.
Most candidates were very familiar with the concept of momentum and answered this
question well. However in part (a) a number of candidates assumed the snow was stationary.
There were many good answers to part (b), but few correct choices of unit in part (c).
E7.
In part (a)(i) many candidates calculated the correct value and gave the correct unit,
although very few realised that momentum is a vector quantity and gave the direction. In part
(a)(iii) the definition of an elastic collision was not well known, many candidates answering in
terms of momentum conservation only. The remaining parts of this question were not well
answered, showing a lack of understanding of momentum conservation in part (b) and the effect
of momentum change in part (c). Many candidates tried to use moments to explain why the boat
tipped rather than moved or answered in terms of force without mentioning momentum. Again,
in part (c) very little reference was made to momentum, although some realised the padding
was, in effect, a crumple zone and knew that increased impact time would lead to a reduced
force. Parts (b) and (c) illustrated the inability of many candidates to apply their knowledge to
unfamiliar situations.
E8.
In part (a)(i) the majority of candidates understood that an object that is not moving has zero
momentum. Most candidates also realised in part (a)(ii) that the luggage with the largest mass
has the most momentum. However, in part (a)(iii) few candidates appreciated that momentum
changed when the direction changed. The unit of momentum was generally known.
E9.
This question proved to be one of the most demanding on this paper. Many candidates
confused momentum with energy in part (a) and few remembered that no external forces should
act. In part (b) most had only a sketchy idea of the physics involved and only scored a mark for
mentioning the fuel combustion. The most common misconception was that the exhaust gases
push against the atmosphere to achieve propulsion. The calculation in part (c) was also poorly
attempted. The majority scored a mark for finding the change in velocity but were not able to go
on to calculate the mass correctly.
E10.
In part (a)(i) most candidates were able to give a partial version of the required equation
but few mentioned that this is the total momentum or gave the direction. Many candidates
ignored the instructions; for example, in part (ii) they chose examples of collisions and similar
events, in part (iii) they gave symbol equations instead of the word equations they were asked
for and in part (iv) threw away a mark by failing to state that the trolleys would move to the right
after the collision. The examiners did not consider that ‘no forces act’ was a sufficient response
in part (v). The response ‘no external forces act’ is quite correct. However it was hardly ever
seen. The answer ‘4000 newtons’ was fairly common. However it was often seen as a
consequence of some completely false equation such as force = mass + time and consequently
received no marks. The examiners are not pleased to note that some candidates are so
confused that they think that 0.00625 N or 6.25 N might be the force of a bullet.
E11.
(a)
(i)
Most candidates were able to give a correct version of the required equation.
(ii)
Most candidates gave the correct numerical answer in this part. However, only a
minority were able to give the correct unit for momentum and most chose to ignore
the instruction to give the direction. Consequently many candidates lost the third
mark.
(iii)
Some candidates showed that they did not appear to understand what was going
on, or had not given themselves time to read the whole question and think about it.
Rather than repeat their numerical answer to part (a)(ii) they chose to modify it,
usually by a factor of two or of ten.
(b)
E12.
The equation required in this part was usually stated correctly, although just
‘momentum’ was sometimes erroneously given for ‘change in momentum’.
(v)
The calculation for this part was usually correct with the correct unit.
This part revealed that an important application of this equation is not generally related to
it. There were some excellent answers which were confident and well expressed.
However, many candidates seemed to have a poor understanding of the concept of
change of momentum and could not relate it to the time and force they had just referred
to. Some claimed that in a crash the momentum of the vehicle is transferred to the
passengers, and that your seat belt prevents you from moving, but no one claimed that
wearing a seat belt was a bad idea.
Parts (i) and (ii) were usually correctly answered with most candidates giving the correct
unit. In part (iii) those who appeared confident that the change in momentum of car A would be
equal to the change in momentum of car B were able to proceed to the calculation of car A'’
speed after the impact. Others, who often seemed to have little understanding of this area of the
Specification, did not get any marks for this part.
E13.
E14.
(iv)
(a) This calculation was not often correct. Many candidates were unable to use the
correct pieces of data appropriately. There was widespread confusion between mass and
force, and even time and velocity were interchanged in many equations. However, some
candidates did complete the calculation well.
(b)
Many candidates recognised that there was more air pushed down per unit time or that
the air was moving faster. Some candidates confused the air moving faster with the toy
moving faster. Although many candidates scored one mark, few candidates were able to
link the increased air movement to the subsequent acceleration in order to score both
marks.
(c)
This was poorly done with most candidates not considering momentum but trying to use
their knowledge of polystyrene to answer the question. Many responses centred on the air
content of the polystyrene or the air resistance slowing it down on its descent.
(a)
(i)
Most candidates were able to use the data and equation provided to produce a
numerical value for the weight of the toy but there were few responses which stated
the correct unit.
(b)
E15.
(b)
E16.
(b)
(ii)
Most of the candidates were aware that the forces involved would need to be
balanced to enable the toy to hover.
(i)
Most candidates were able to explain the term ‘acceleration’ however, there were
many references to ‘move’, ‘increase’ etc without any elaboration.
(ii)
This was question was generally answered correctly however, there were a number
of incorrect references to ‘south’.
(iii)
Half of the candidates understood that the momentum would increase but few could
give a valid reason why.
(a)
(i)
Most candidates stated that velocity is speed in a given direction. Few
candidates stated that velocity is either speed in a straight line or velocity = speed ×
time.
(ii)
A good proportion of candidates obtained 64 metres but many candidates correctly
obtained 16 and 4 from the graph and then divided the two numbers. Some
candidates did a longer calculation and obtained the complete area under the graph.
(iii)
This question was well done with the majority of candidates scoring both marks.
However some candidates either misread the question and redrew graph 1 or were
at least one small square out in their accuracy.
(iv)
Many candidates were able to score a mark however the majority simply quoted the
law of conservation of momentum.
Many candidates did not score any marks here and wrote about whiplash and trying to
avoid serious injuries. Some realised that if the force was to be constant over the same
time period then it must be smaller. Some candidates were familiar with the equation
linking force and rate of change of momentum but were unable to link this with any logical
explanation.
(a)
(i)
Most candidates were able to identify velocity or speed but weight was often
given as an incorrect alternative to mass.
(ii)
A pleasing number of correct answers given. However a significant number of
candidates tried to complete a calculation that involved total mass and a velocity
value.
(i)
The substitution of values and the subsequent calculation was handled well by the
majority of candidates who scored maximum credit.
(ii)
E17.
(a)
(ii)
Only a minority of candidates understood that the momentum was conserved.
(i)
The calculation was well done with most candidates obtaining 210. However,
only half of those obtaining this correct answer were also able to give the correct
unit.
Most candidates who scored 2 or 3 marks for part (a)(i) obtained the correct answer.
Those who did not tended to multiply 210 by 0.25 instead of dividing. A number of
candidates subtracted 6 or 35 from 210 before dividing by 0.25 thereby losing both
marks.
(b)
This was either done very well or very poorly. It was not always clear that the rubber tile
increased the time to stop and some candidates went straight to the second marking point
i.e. increases the time for the change in momentum. Occasionally when a poor answer
was written the candidate managed to salvage a mark by finishing with ‘the force is
reduced’. A lot of candidates mentioned ‘air gaps’ and ‘bouncing/cushion effect,’ gaining
no credit.
(c)
The answers were very variable. Many were very vague and referred to accuracy rather
than reliability or human error rather than anomalies. The range of thicknesses being
insufficient was seldom referred to.
(d)
This was generally done well; a few candidates just mentioned recycling without
explanation and gained no credit. The most popular answers concerned either burning or
use of land-fills, a few candidates mentioned deforestation of rubber trees but these were
not penalised!
E18.
(a)
(b)
(i)
Most candidates were able to describe the relationship between the maximum
height from which a child could fall without serious head injury and the appropriate
thickness of rubber safety tiles in a playground.
(ii)
The identification from the graph of the correct thickness for a fall of 2m was well
done with the second marking point being scored most often by an answer that
referred to use of the graph.
(i)
Few candidates scored this mark. The vast majority of candidates chose the answer
‘the work done to stop’.
(ii)
Just over half of the candidates knew that ‘the force on’ the child would reduced.
E19.
(a) Most candidates that correctly chose the skier with the greatest mass as the person
with greatest momentum also supplied the appropriate reason for their choice. However a
significant minority of candidates chose X or Z and gained no marks.
(b)
E20.
The majority of candidates were aware that acceleration would produce an increase in the
momentum of the three skiers. However there was a large number of candidates that
clearly had not read the question correctly and gave answers in terms of an increase in
speed.
Foundation Tier
(a)
(b)
(i)
This was well answered with most candidates gaining both marks.
(ii)
It is surprising that only just over 50 % of the candidates knew the unit of
acceleration.
(iii)
For a standard piece of recall it was surprising that only 50 % of candidates scored
a mark.
(iv)
Less than 50 % of candidates drew the correct line and gained 2 marks. Many
candidates did not take into account the final velocity of 9 m/s. Others did not relate
the idea of constant acceleration to a straight line.
(i)
Candidates that chose the correct shoe of the three on test often gave a suitable
reason for their choice to achieve 2 marks, but then failed to appreciate that this
shoe was the best on all of the listed types of surface.However nearly 50% of
candidates were unable to interpret the bar chart correctly and chose either A or C.
(ii)
Most correct answers were in terms of human variability but many candidates
mentioned the robot’s consistency. A significant number of candidates did not
recognize the importance of the word ‘reliable’ and answered in terms of sensor
accuracy.
Higher Tier
(a)
(i)
Most candidates obtained the correct answer although a few candidates multiplied 9
× 2 instead of dividing.
(ii)
The majority of candidates knew that the unit of acceleration was m/s2.
(iii)
The majority of candidates gave the correct answer.
(iv)
Most candidates produced a straight line with a ruler from the origin to (2,9). Those
who did not obtain full marks were generally not accurate enough. A number of
candidates did not link the idea of constant acceleration with the need to draw a
straight line.
(b)
E21.
(b)
E23.
(i)
Many candidates correctly chose B but then failed to compare this shoe with both A
and C or mention that it was the best shoe on all three surfaces. However a
significant number of candidates did score all three marks.
(ii)
The majority of candidates obtained the mark, usually giving answers in terms of
variations in human athletes eg weight / size of foot may be different and they run at
different speeds. A common fault was to be too vague and say that the robots are
more accurate or they remove human error; a few answered with the standard
response ‘it’s a fair test’ without qualifying the statement.
(a)
(i)
The majority of candidates correctly substituted the data into the equation and
calculated a correct answer.
(ii)
This was generally answered well. Unfortunately, a number of candidates chose to
draw several arrows rather than the requested single arrow.
This part of the question was answered well but there were some instances where
candidates had given the momentum as 900 then explained the reason by substituting
numerical values for the mass and velocity and presented the equation ‘900 × 0 = 900’.
(a)
(b)
(i) There was much confusion throughout this question between momentum and
energy. Clearly a large number of candidates consider them to be the same. Less
than half of the candidates gave a correct answer. Those that did often scored the
mark with a simple statement such as ‘momentum before = momentum after’.
(ii)
Very few candidates answered this correctly. Incorrect answers often talked about
elastic and inelastic collisions in terms of energy conservation. There were also a lot
of references to crumple zones, walls, immovable objects etc. Those candidates
gaining credit often simply stated an ‘external force acts’.
(i)
Many candidates scored 1 mark for calculating the momentum of the car either
before or after. However, many candidates failed to develop the idea and subtract
the two numbers. Units proved troublesome; far too often it was given as kg/m/s or
kgm/s2, occasionally answers were given as N.
(ii)
The better, well prepared candidates scored both marks. However, the incorrect
answer 10 - 2 = 8 m/s was very common. Too few candidates seemed able to write
down ‘momentum before =; momentum after’ and hence obtain the answer.
E24.
(a) This question was answered well with a majority of the candidates achieving both
marks. However, there were some responses which indicated that candidates had
interpreted ‘m/s’ as being momentum per second. Some candidates thought that R had
the most momentum because it was in front.
(b)
(c)
(i)
Most candidates were able to multiply the mass by the velocity correctly. However, a
significant minority of candidates substituted the numbers correctly but seemed not
to have a calculator to enable them to give the correct answer.
(ii)
The majority of candidates responded correctly with errors being equally split
between the two wrong answers provided. A few candidates had unfortunately tried
to split the correctly paired unit circling only either kg or m/s.
(i)
This question was answered well with most candidates responding in terms of an
increase in reaction time although some incorrect responses were clearly directed
towards distance, rather than time.
(ii)
This question was poorly answered mainly due to candidates not answering the
question set ie, what happens to braking distances in wet conditions.
Candidates wrote excellent responses in terms of aquaplaning, skidding, lack of
traction, wet brakes, the need to brake earlier, the need for less braking force, the
increased possibility of accidents, the need to drive slower, etc. However, these
responses failed to address the question.
E25.
(a) Many candidates obtained the correct answer having correctly calculated the
resultant force as 1155 N. Correct calculation of the force 1155 N then multiplying by the
mass of 275 kg was a common error gaining just one mark. The use of an incorrect force
with the correct method, gained many candidates one compensatory mark.
(b)
(i)
Many candidates failed to understand that the question was referring to the validity
of the data with many answers given in the form of a conclusion rather than
answering the question about valid data. Those candidates who realised the
question was about the data, answered mainly in terms of the reliability of police
files (YES) or on the lack of information about ages (NO). Many candidates quoted
the number of files in the source, but as they failed to express whether this was a
large or a small sample, failed to score a mark for this. There was also evidence of
much rewriting of answers, mostly to little or no advantage.
(ii)
Just over half of candidates gained one mark for describing how the smaller
motorbikes had more accidents and a small minority of candidates went on to note
how there were fewer smaller bikes than larger bikes, or calculated ratios.
(c)
E26.
E27.
(i)
Very few candidates gained full marks on this question, in spite of it being a well
examined aspect of the course. A change in context does disguise what is needed
to all but the highest scoring candidates, in spite of the stem referring to momentum.
Over half of candidates scored zero. The quality of the explanation was often poor.
There are still a large number of answers referring to cushioning the impact rather
than reducing the force. The‘decreases rate of change of momentum’ is the most
frequently missed mark. A number of candidates confused their response with
references to kinetic energy and stopping distances.
(ii)
Most candidates gave the answer that the new safety barriers would save lives, or
reduce injuries, which gained the mark. Those who thought that 17m/s was too slow
to crash or cause serious injury had confused the unit with mph.‘Money could be
better spent’ was rarely a complete answer and so did not score a mark very often.
(a) This question was generally answered well with virtually all candidates recognising
that drinking alcohol would increase the chance of an accident occurring. However, a
number of candidates failed to achieve the second mark due to identifying that there
would be an alteration of the driver’s reactions, but not whether the alteration would be
positive or negative. Another common error was to state that the ‘driver’s reaction time
decreases’.
(b)
Virtually all candidates understood the idea that a fair test was required to choose the best
barrier to slow a car and not break. However few were able to explain how a change of
the three different variables would affect the outcome and prevent a valid set of results
being produced, that would provide evidence to which crash barrier was the best of the
three under trial.
(c)
Just over four fifths of candidates chose the correct answer.
(a)
(ii)
(i) Most candidates were aware that the lorry would have the greatest momentum
by reason of its greater mass. Vague responses, such as‘the lorry is bigger’, did not
gain a mark. Some candidates took advantage of the relevant equation printed on
the same page and calculated the momentum of the three vehicles. Incorrect
responses generally involved the motorbike and indicated that the candidates were
confusing momentum with the ability of the motorbike to accelerate faster than the
other two.
This part question was generally answered well by those candidates with access to
calculators. Candidates should be encouraged to check their calculations carefully
as there were a number of instances of errors occurring in the transfer of the
numbers from the question stem to the lines provided, to show their method of
calculating the momentum of the motorbike.
(b)
(i)&(ii)Just over nine tenths of candidates correctly answered that the kinetic energy would
increase but they had less success in giving an appropriate reason. Most of the
incorrect responses were in terms of the motorbike accelerating which had been
stated in the part question stem. There were also many vague responses involving
changes of force, power, friction, engine efficiency, etc.
(iii)
(a) It was surprising that only a quarter of the candidates correctly answered ‘direction’
with ‘velocity in m/s’ a very common response. A small minority of candidates did not
attempt this part question. It may be that many of these candidates did not look at the
page carefully enough to realise there was a question at the top.
E28.
E29.
Just over three quarters of candidates gained all three marks. Those that did not
often drew a diagonal line from (4, 14) up to 20 m/s on the y-axis but the lines did
not hit (6, 20) and were not subsequently continued horizontally to 8 s on the x-axis.
(b)
Generally this question was well answered by the majority of students, with just over twothirds scoring full marks. However, a large minority of students couldn’t substitute values
from the text into a given equation correctly, often confusing time and speed. Some
candidates didn.t recognise that the standard unit for mass is the kg and needlessly
changed mass from kg into g, losing marks.
(c)
Many candidates concentrated on the details of operation of airbags rather than the
explanation of how they reduce risk of injury. There was little mention of ‘momentum’ from
many candidates, and over two-fifths scored zero. Some candidates answered in terms of
conservation of momentum, indicating that they had learned some physics but were not
aware when to apply it. Of those that did give creditworthy answers there was often
confusion over ‘reducing momentum’ and ‘reducing the rate of change of momentum’.
(a)
(i) This part question was answered very well with a large majority of candidates
scoring both marks. However for those candidates failing to score the marks the
main problem seemed to be lack of a calculator, or incorrect use of a calculator,
evidenced by the use of lengthy iterative processes or missing zeros in their final
answer.
(ii)
Only a small minority of candidates were aware that the momentum of the vehicles
were conserved in the collision, the most incorrect common response being that the
momentum had decreased to zero.
(iii)
Most candidates failed to appreciate that a stationary car has less momentum than a
moving car.
(b)
E30.
Just over half of the candidates scored both marks.
(a) About two thirds of students scored this mark, showing that they had learnt that
momentum has direction. A significant number of students ignored the information given
in the question and stated that the two teenagers had different speeds or different mass.
(b)
(c)
E31.
(i)
Over two fifths of students scored this mark, giving a clear statement explaining
momentum conservation, e.g. ‘momentum before = momentum after’ with many
giving atextbook answer including the proviso that no external forces act. Some
students suggested that the momentum was used up or ran out, or gave poor
answers aboutforces and energy. Some students attempted to apply the rule to the
particular case of the skateboard, explaining about the teenager and the boy having
equal and/or opposite momenta. Unfortunately they generally did not go on to say
that the (total) momentum had not changed.
(ii)
Over two fifths of the students showed an excellent understanding of momentum
conservation and presented clear working leading to a correct three mark answer.
Another two fifths of students gained no marks at all. Their working showed little
grasp of the mathematical aspects of momentum. There were many different wrong
answers, the most common being 10/0.4 = 25, with no mass values involved at all.
Of the remaining students, most gained a single mark for calculating the teenager’s
momentum. Very few students obtained the second compensation mark by either
stating the conservation of momentum or giving a numerical expression of this.
Many students showed misconceptions about ‘force’ and ‘energy’, e.g. stating that without
a force pushing it the board no longer has any energy, that it needs a force to keep it
moving, or that friction is stronger than the kinetic energy. Very few connected friction with
the work done against it. Too many wrong answers were comparing this question with
question (b) and mentioning an increasing frictional force. As a result about two thirds of
students did not score on this question. On the other hand, a few students showed clear
understanding of the key terms and gained both marks for saying that kinetic energy is
transferred as heat because of the friction force. About a third of students gained a single
mark, usually for correctly referring to a friction force or, less often, for stating that kinetic
energy is transferred by heating.
(a) It was disappointing that only just over half of students could identify mass and speed
as the factors that affect kinetic energy.
(b)
(i)
This was well answered by nearly all students. Most students recognised that
because A was stationary or not moving that there would be no momentum.
(ii)
E32.
(a) A large majority of students (85%) scored full marks demonstrating an ability to use
the given equation correctly. About 3% of students were able to substitute the values
correctly into the equation but then made mistakes with the arithmetic. Approximately 12%
of students were unable to correctly substitute values; often using v instead of v2
(b)
(c)
E33.
This was correctly answered by nearly all students, with most correctly writing down
the numerical values of mass and velocity before completing the multiplication.
(i)
While most students were able to calculate a momentum using the given equation
only about 23% of students recognised that they needed to find the difference
between the initial and final momenta. Very few correctly calculated the change in
velocity to be 60m/s to gain the compensation mark. Most of the 75% of students
who scored zero on this part question only calculated the final momentum, albeit
correctly, but unfortunately this was not creditworthy in the context of this question.
Some students who did recognise that a change in momentum needed to be
calculated confused signs and ended up with a change in momentum of zero thus
demonstrating a lack of understanding of the concept.
(ii)
Of the 23% of students that answered part (b)(i) correctly only a small number then
made errors in this question. The vast majority of students managed to substitute
their answer to (b)(i) into the equation for force and calculate the answer correctly,
gaining an ‘error carried forward’ mark. Approximately half of the students who failed
to score here did so because their answers to part (b)(i) were zero, making it
impossible to gain this mark. There were a few students who at this stage realised
that their answer of zero earlier must be incorrect so they deleted the calculation
that resulted in a force of zero and came up with the correct figures, but failed to
amend (b)(i) to match. Just over 83% of students scored this mark.
Just over half of the students gained some credit on this question but only 28% scored
both marks. Of these about half gained the marks by correctly stating that ‘the rate of
change of momentum had decreased’. Other students were less concise but did tie-up
increased time to the change in momentum. Of the students who did not score fully on this
part question many offered confused statements, that the change in momentum was
smaller, not realising that it is the same change in momentum to bring the ball to a stop or
offered vague statements about the time taken slowing down.
(a) Nearly 60% of students scored all three marks. However, “standing still” or
“stationary” was a common wrong answer to A, even though the students were told the
car was moving. Often, in B and C, students calculated the resultant force and did not
describe the motion, just the direction; forwards for B or backwards for C.
(b)
(c)
E34.
(i)
Most students correctly gave the distance travelled while braking. Some students
correctly wrote about the distance travelled after braking, or distance travelled in the
braking time. A common wrong answer was to involve total distance travelled before
the car stops, since this would include the reaction time. Many students lost the
mark by putting a list of “braking and stopping distance”.
(ii)
Only 25% of students scored this mark. Students often wrote about factors affecting
stopping and braking distance; ‘bad weather conditions’ was a very common wrong
answer. Also tiredness, being drunk, condition of road and state of vehicle were
often given.
(i)
This mark was for giving both 5000 N and a clear direction. A lack of a simple arrow
drawn in the correct direction kept many students from gaining this mark. Some
students simply wrote ‘a very large force’ rather than quantifying it. A common
incorrect answer was “5000 N on the car”. One of the most common responses was
“5000 N towards the car”, which gained credit. Some students failed to include 5000
N in their answer, just stating that the resultant force was equal and opposite.
(ii)
This question is about a dummy being used to measure/record the effects of
impact/force. Many students wrote around this answer. “To see the force” was a
common incorrect answer. Many students answered in terms of how much damage
the dummy received, not mentioning measurement of the forces causing the
damage and many students wrote about “impact”, instead of “force”, and did not
gain credit for their answer.
(iii)
A great number of students knew how to find the gradient of a velocity-time graph in
order to calculate the acceleration, However, they failed to use only the straight line
part of the graph - between 2 and 4 seconds. As a result, 10/4 was a common
answer, giving 2.5 instead of 4. Often, the unit was the only credit-worthy part of an
answer, although there were a number of mps, mph, km/s, etc. An answer of 40 was
also quite common, multiplying 10 by 4. About half the students gave the correct
unit; although m/s was a common incorrect answer. Some students drew a triangle
correctly, but failed to use it, gaining one mark only. Some students correctly found
2 and 8, or 1 and 4, but then didn’t know how to calculate the acceleration; obtaining
16 or 0.25.
(a) Just over 67% of students scored all three marks. A further 25% scored two marks.
The most common error was to identify car A as being stationary, this was despite the
word ‘moving’ being in bold in the stem of the question.
(b)
(i)
Nearly 90% of students scored this mark.
(ii)
Just over 90% of students scored this mark.
(iii)
This was not so well answered, with only 43% of students realising that the forces
would be equal.
(iv)
E35.
The majority of students (92%) realised the reason for attaching the sensors to the
dummy.
(a) Just over 67% of students scored all three marks. A further 25% scored two marks.
The most common error was to identify car A as being stationary, this was despite the
word ‘moving’ being in bold in the stem of the question.
(b)
(i)
Nearly 90% of students scored this mark.
(ii)
Just over 90% of students scored this mark.
(iii)
This was not so well answered, with only 43% of students realising that the forces
would be equal.
(iv)
The majority of students (92%) realised the reason for attaching the sensors to the
dummy.