7
Different forces
Ka-1
Name
Class
Date
1 Write down three things that forces can do.
2
a
What CF is the name for forces where things have to be touching to have an effect?
b
What F is a force that happens when two things rub against each other?
c
What WR slows down objects moving in water?
d
What U force makes things float?
e
What G is a force that pulls things downwards?
f
What M is a force that attracts iron?
g
What N is the unit for force?
h
What M is measured in kilograms?
3 Write down the names of three contact forces.
4 Write down the names of three non-contact forces.
I can…
●
recall the names of simple forces
●
classify forces as contact and non-contact
●
recall the effects of forces on an object.
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1
7
Forces in action
Ka-2
Name
Class
Date
Use the apparatus provided to help you to fill in the gaps on this sheet. The words you need are
given in the brackets.
1
Apparatus
●
two magnets
(attracting/repelling) each other.
The magnets are
The force is strongest when the magnets are
The name of this force is
(close together/far apart).
(friction/gravity/magnetism).
What will happen if you turn one of the magnets around?
2
Apparatus
●
ice cube
●
wooden block
Clear up any spilled
water straight away.
The force of
across the desk.
It is
(friction/gravity/magnetism) tries to stop the blocks moving
(easier/harder) to push the block of ice, because the ice is
(wet/dry).
3
Apparatus
●
natural string
●
plastic string
It is
has a
(harder/easier) to tie a knot in the plastic string. The plastic string
(rough/smooth) surface so there is less
(friction/gravity/magnetism) to hold the knot in shape.
Page 1 of 2
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2
7
Forces in action
Ka-2
4
Apparatus
●
spring
The force from the spring gets
The spring is
(bigger/smaller) if it is stretched further.
(pulling/pushing).
5
Apparatus
●
force meter
●
object
Weigh the object. How much does your object weigh?
The force of
downwards.
(friction/gravity/magnetism) is pulling the object
6
Apparatus
●
two sheets of paper
The paper takes
The air resistance is
(less time/more time) to fall if it is crumpled up.
(more/less) when the paper is crumpled up.
I can…
●
recall the names of simple forces
●
describe the effects of different forces on objects.
Page 2 of 2
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3
7
Ka-3
Ideas about forces
A Greek philosopher (thinker) called Aristotle (374–322 BCE) was one of the first people to think in
a scientific way about forces.
Aristotle thought that everything was made up of different combinations of four ‘elements’: earth,
air, fire and water. Each element had its own natural place, and this could explain why things
floated or fell.
1 You can see flames rising up from a bonfire. Suggest where Aristotle would have said the
‘natural place’ was for fire.
2 According to Aristotle:
a
why does a drop of water fall through the air, but not through the ground
b
why does a stone sink if you drop it into water?
3 Wood floats on water. Which of the four ‘elements’ do you think Aristotle thought wood was
made from? Explain your answer.
4 According to modern scientists:
a
why does a stone fall if you drop it
b
what keeps a block of wood floating on water?
I can…
●
identify observations that are explained by ideas
●
recall the names of some simple forces.
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4
7
Ka-4
Hazards and risks
Some sports are more dangerous than others. You are more likely to have a serious accident if
you go rock climbing or kayaking than if you play football or take part in athletics. But adventure
sports are becoming more and more popular because modern equipment can make them safer.
Rock climbers use ropes and other equipment so
that if they fall off a mountain, they do not fall
very far. The equipment they use is made just for
rock climbing, and the manufacturers test it all
carefully to make sure it is strong enough for its
purpose. Climbers also check their equipment
before using it, to make sure it has not been
damaged. It isn’t enough just to have the right
The CE label on this climbing helmet shows that it
equipment. You must also know how to use it
meets European standards.
properly.
People who run factories, laboratories or schools
must carry out risk assessments to make sure
that the activities that go on there will be as safe
as possible. Outdoor centres also do risk
assessments for activities such as rock climbing.
A risk assessment first considers all the possible
hazards (dangers) that could occur. Then it looks
at how likely the hazards are to cause harm – this
is the risk. Doing a risk assessment can help
people to work out how to reduce the risks, so
that the activity is as safe as possible.
People who do adventure sports do not normally
write out risk assessments, but they have usually
thought about them before they set off.
1 Suggest why rock climbers:
a
use ropes
b
wear helmets
c
need harnesses
2 How could a manufacturer test the following types of equipment to make sure they were
suitable for use in climbing?
a
ropes
b
helmets
c
harnesses
3 What is the difference between a hazard and a risk?
4 Write down some hazards that exist for the following activities. For each one, say how the risk
could be kept as low as possible.
a
Going on a bike ride in the mountains, where you will be miles from the nearest road.
b
Kayaking to an island 10 miles from the coast.
I can…
●
state the meanings of risk and hazard
●
identify ways of controlling risks.
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5
7
Forces and mass 1
Ka-5
Name
Class
Date
1 The drawing shows some people base jumping
(using parachutes to jump off solid objects).
Draw labelled arrows on the diagram to show
where the following forces are in action.
a
air resistance (label this arrow A)
b
friction (label this arrow F)
c
gravity (label this arrow G)
d
water resistance (label this arrow W)
e
upthrust (label this arrow U).
2 a
b
Which force mentioned in question 1 is a non-contact force?
Name two other non-contact forces.
3 Some of these statements describe mass, some describe weight, and some apply to both.
Tick the correct boxes in the table.
Mass
a
The amount of matter in an object.
b
Measured in newtons.
c
The size of the gravity force pulling down on something.
d
Measured in kilograms.
e
This would not change if an object was taken to the Moon.
f
This would get smaller if an object was taken to the Moon.
g
Gets less when you go to the toilet.
h
Increases when you eat something.
Weight
Mass
and
weight
I can…
●
identify places where different forces are found
●
classify forces as contact and non-contact
●
explain the difference between mass and weight.
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6
7
Ka-6
Forces and mass 2
1 The drawing shows some people base
jumping (using parachutes to jump off
solid objects).
Describe where the following forces are
acting, and in which direction.
2
a
air resistance
b
friction
c
gravity
d
water resistance
e
upthrust
a
Which force mentioned in question 1 is a non-contact force?
b Name two other non-contact forces.
3 Write down three things that forces can do, and give an example of each one.
4 What is the difference between mass and weight?
5 a
Describe one thing you did this morning that increased your mass.
b
Write down one thing that can decrease your mass.
c
How do these things affect your weight?
d
State one way in which the weight of an object can be changed without changing its
mass.
I can…
●
identify places where different forces are found
●
classify forces as contact and non-contact
●
explain the difference between mass and weight.
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7
7
Measuring masses
Ka-7
1 These supermarket scales measure the
weight of fruit or vegetables put in the pan.
The scale is marked in kilograms.
a
Explain why this is wrong from a
scientific point of view.
b
Explain why this does not really matter
to a customer in the supermarket.
2 These traditional kitchen scales come with
a set of standard masses. These are
marked in kilograms. A kilogram mass is
made by comparing its mass with the
mass of a ‘standard’ kilogram.
a
Do these scales find the mass or the
weight of the food?
b
Explain how to use these scales.
c
Explain how the scales find the mass
of the ingredients.
3 Look at the scales in questions 1 and 2.
Which ones could be used to find the
correct mass of an object on the Moon?
Explain your answer.
4 The kilogram was introduced as an official
unit of mass for buying goods in the UK in
1965. Before that, all goods had been sold
in pounds and ounces (part of the imperial
system of measurement). 1 pound is about
the same mass as 0.454 kg. The table
shows some of the other imperial units.
a
A person has a mass of 10 stone.
What is their mass in kg? (Hint:
Convert the mass to pounds first, then
to kilograms.)
b
A person buys a hundredweight of
coal. What mass of coal have they
bought in kilograms?
c
A newborn baby has a mass of 5 lbs
4 oz. What is its mass in kg?
d
Explain why it is useful for all scientists
to use the same units for measuring
mass.
Unit
Abbreviation Conversion
ounce
oz
16 oz = 1 lb
pound
lb
14 lb = 1 st
stone
st
8 st = 1 cwt
hundredweight
cwt
I can…
●
explain the difference between mass and weight
●
convert measurements between different units.
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8
7
Springs
Kb-1
Name
Class
Date
Fill in the gaps in these sentences using words from the box. You may use each word once, more
than once or not at all.
compress
elastic
elastic limit
proportional
extension
stretch
original length
plastic
stretched length
1 The forces on spring A will
it.
2 The forces on spring B will
it.
3 a
Length C is the
spring.
of the
b
Length D is the
spring.
of the
c
Length E is the
spring.
of the
4
When the force is removed from a spring it
.
returns to its
. It is
.
5 The graph shows how the extension of a spring
changes when the force on it is changed.
a
In part F of the graph, the extension is
to the force.
b
In part G, the spring has been pulled past
its
original shape.
. It will not return to its
I can…
●
describe how the extension of a spring depends on the force applied.
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9
7
Investigating stretching 1
Kb-2
Your teacher may watch to see if you can:
●
follow instructions to set up apparatus
●
make accurate measurements.
Aim
Find out if springs and elastic bands stretch in the same way.
Hypothesis
The length of a spring and an elastic band will both depend on the force being applied.
Method
Apparatus
●
stand and 2 clamps
● G-clamp
● box with newspaper
●
●
mass holder and masses
elastic band
● ruler
● spring
Put a box of
crumpled
newspaper
beneath the
weights so they
cannot fall on
your feet.
A Set up your apparatus like this.
B Adjust the ruler in the clamp so that the zero is level
with the bottom of the spring.
C Hang the holder on the spring and measure the
length. If you have set up the ruler correctly in step B,
the reading on the ruler will tell you the extension of
the spring.
The holder has a mass of 100 g. Write your result in
the table.
D Put more masses on the spring and measure its
extension each time. Your teacher will tell you the
maximum mass you should use.
E Repeat steps B to D using an elastic band instead of
a spring.
Recording your results
1 Record your results in a table like this:
Mass (g)
Weight (N)
0
0
100
1
Extension of spring
(cm)
Extension of elastic
band (cm)
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10
7
Kb-2
Investigating stretching 1
2 Plot a graph of your results on graph paper. Plot the results for the spring and for the elastic
band on the same axes. You will need to use axes like this:
Considering your results/conclusion
3 a
Describe the shape of the line on your graph for the spring.
b
Describe the shape of the line for the elastic band.
c
Describe the similarities and differences in the way the spring and the elastic band
stretch.
4 Look at the hypothesis at the top of this worksheet.
a
Is the hypothesis correct?
b
Write a sentence that is a better description of what you have found.
I can…
●
make and record observations
●
present data in an appropriate graph
●
draw conclusions from evidence.
Page 2 of 2
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11
7
Investigating stretching 2
Kb-3
Your teacher may watch to see if you can:
●
make accurate measurements.
Aim
To find out if all materials stretch in the same way.
Introduction
You are finding out if the results for the different materials show
the same pattern, not comparing how far each material stretches.
The apparatus you need depends on how stretchy the material is
that you are testing.
This apparatus is the simplest to use:
Put a box of crumpled
newspaper beneath the
weights so they cannot
fall on your feet.
This apparatus is better if the material you are
testing does not stretch very much.
Hypothesis
1 Write a hypothesis that you can test.
Planning
2 Write a method for your investigation. You will need to think about these things:
● Which materials will you test?
● What masses will you need?
● How will you stay safe while you are carrying out your investigation?
● Will you need to repeat any measurements?
3 Make a table ready for your results.
4 Show your method to your teacher before you start.
Recording your results
5 Record your results in your table and plot a scatter graph to show your results. Draw a curve of
best fit on your graph. (This is a smooth line that goes through as many points as possible.)
Considering your results/conclusion
6 a
b
Describe the shape of the line on the graph for each material that you tested.
Do the graphs for all the materials show the same pattern?
7 Write a conclusion for your investigation.
8 Was your hypothesis correct?
Evaluation
9 Are there any results that are not on the lines on your graphs? If so, why do you think this
happened?
10 If you had time to do your investigation again, could you improve it? Explain how.
I can…
●
●
plan a safe and fair investigation
make and record observations
●
●
present data in an appropriate graph
draw conclusions from evidence.
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12
7
Kb-4
Make a force meter
Introduction
When you pull on a spring, its extension is proportional to the force up to the elastic limit of the
spring. You can use a spring as a force meter if you know how much it stretches for different
forces.
You are going to calibrate a spring so that you can use it as a force meter.
Method
Apparatus
●
stand and 2 clamps
●
mass holder and masses
●
ruler
●
G-clamp
●
spring
●
object to weigh
A Set up your apparatus like this.
B Adjust the ruler in the clamp so that the zero is level
with the bottom of the spring. This allows you to read
the extension directly from the ruler when you add
masses.
C Write down the extension of the spring with five
different masses hanging on the spring. Make sure
you do not go past the elastic limit of the spring (your
teacher will tell you what this is). Write your results in
a table.
D Draw a scatter graph to show your results. You
should put weight on the horizontal axis and
extension on the vertical axis. Draw a line of best fit
through the points. This is a straight line through the
points, with half the points on each side of the line.
E You can use your force meter to weigh other
things. There are two ways of doing this:
a Hang an object on the spring and measure
the extension. Then use your graph to find
its weight, like the one on the right.
b Make a scale to stick over the ruler, so that
you can read the weight directly from the
scale.
Considering your results
1 Compare the weight of the object you measured with the weight obtained by different groups
for the same object. How close is your value to the one obtained by other groups?
2 How could you make your force meter more accurate?
3 Explain why it is important that you do not:
a
stretch the spring beyond the elastic limit when you are calibrating it
b
try to weigh something that will stretch the spring beyond its elastic limit.
I can…
●
present data as a line of best fit on a scatter graph
●
use data on a scatter graph.
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13
7
Different kinds of spring
Kb-6
There are many different kinds of spring. All springs are objects that change shape when a force is
applied to them, and return to their original shape when the force is removed. There are many
different uses for springs.
Use the internet to find out about the different shapes that springs can have, and how they are
used.
1 Your task is to present information about the different kinds of springs and their uses. Illustrate
each kind of spring, and write two or three sentences about its uses. If possible, explain how
the shape of the spring helps it to do its job.
2 Choose who your presentation will be for. For example, you could be:
● working for a spring manufacturer and explaining the types of springs that people could buy
from you
● training engineering students who may need to use springs
● showing younger students the different uses of springs.
Choose a way of showing the information suitable for your audience. For example you could
make a computer presentation, a leaflet or a poster.
Here are some spring names and uses to get you started:
Types of spring
Uses of springs
●
coil spring
●
weighing things
●
conical spring
●
storing and releasing energy
●
leaf spring
●
holding things in place
●
running blades
●
making furniture and beds comfortable
●
power spring
●
●
bungee cord
reducing bumps in cars or other
vehicles
●
torsion spring
●
split wire rings
●
spring clips/circlips
I can…
●
find relevant information about springs
●
present information in a suitable way for an audience.
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15
7
Stretching springs 1
Kb-7
Name
Class
Matilda and Ravi carried out an experiment with springs.
They put different weights on the spring and measured the
length of the spring each time.
The table shows some of their results.
1
Fill in the missing unit in the table and on the label on the
graph.
2
Draw a graph to show the results.
3
Which is the best conclusion for their experiment?
Tick one box.
Date
Weight (___)
Extension (cm)
0
10
2
14
4
18
6
22
8
26
10
30
 The bigger the mass, the larger the weight.
 The larger the weight, the longer the spring.
 The longer the spring, the bigger the weight.
 The shorter the spring, the bigger the weight.
4
Ravi uses the same spring and hangs some different
objects from it. He uses his graph to work out the weight
of each object. The table below shows his results.
Fill in the missing weights.
Object
Length of
spring (cm)
Weight of
object (N)
A
26
8
B
14
C
22
D
16
E
28
I can…
●
present data as a scatter graph
●
draw a conclusion
●
use data from a scatter graph
●
describe how the extension of a spring depends on the force applied.
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16
7
Stretching springs 2
Kb-8
Matilda and Ravi carried out an experiment in class that showed how a spring was extended
(stretched) by different forces.
Their results are shown in the table below.
Mass (g)
Weight (force) (N)
Length (cm)
Extension (cm)
0
0
3
0
200
2
7
400
4
11
600
6
15
800
8
19
1000
10
23
1 Draw a table with columns for weight and extension. Copy the weights from the table above
and work out the extensions.
2 Plot a scatter graph of their results on graph paper. Put weight on the horizontal axis and
extension on the vertical axis.
3 Imagine that you make a force meter with this type of spring. What range of forces could you
measure?
4 Ravi used his force meter to weigh some other objects.
He wrote down the extension of the spring when he hung
each object on it.
Work out the weight of each object using your graph.
Object
Extension
(cm)
A
2.0
B
19.0
C
4.5
D
6.5
5 Matilda and Ravi wrote this conclusion:
This experiment shows that a spring stretches by the same amount each time
a 200 g force is added to the other weights.
They made mistakes in their conclusion. What were they?
I can...
●
present data as a scatter graph
●
draw a conclusion
●
use data from a scatter graph
●
describe how the extension of a spring depends on the force applied.
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17
7
Kb-9
More than one spring
Some students investigate the extension of the different combinations of springs shown below.
All the springs are identical. The table shows their results.
Spring
arrangement
Extension with a
10 N force (cm)
A
5
B
2.5
C
10
The extension of B is half the extension of A, because the 10 N force is shared between the two
springs. Each spring stretches as far as it would if it had only a 5 N force on it.
The extension of C is twice the extension of A because the same force is being applied to both
springs. The bottom spring stretches because of the weight of the masses hanging on it. The top
spring stretches because it is being pulled downwards by the bottom spring. The 10 N force
causes both springs to stretch by 5 cm, so the total extension is 10 cm.
1
A 20 N force is applied to the spring arrangements in
A, B and C. Explain what the extension will be for
each arrangement.
Three more arrangements of springs are shown on the
right. All the springs in arrangements A to F are identical.
2
What will the extension of arrangement D be when a
10 N weight hangs on it? Explain your answer.
3
A spring is made of the same material as spring A and
is made in the same way, except that it is twice as
long. Suggest what its extension will be when a 10 N
weight hangs on it.
4
a
Explain what the extensions of arrangements E
and F will be when a 30 N force is applied.
b
What assumption have you made in your answer
to part a?
5 The bottom drawing on the right shows a bicycle
saddle with two springs.
a
Suggest why the springs are used.
b
A manufacturer wants to replace the springs
shown with a single spring. Explain how the
springs would have to be changed to provide the
same performance for cyclists using the saddle.
I can…
●
use my knowledge of springs in new contexts.
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18
7
Friction
Kc-1
Name
Class
Date
1 Tick the boxes to show when friction is useful and when it is not useful.
2
Useful
Not useful
a
Friction between your shoes and the floor.


b
Friction between the tyres of a bicycle and the road.


c
Friction in the axle of a bicycle wheel.


d
Friction between skis and the snow.


e
Friction between brake pads and a bicycle wheel.


Oil and grease are
to reduce friction.
that help
3 Friction can be increased or decreased. Tick the boxes to show how each change will affect
the friction.
4
Increase
friction
Decrease
friction
a
Using a special rubber for climbing shoes.


b
Rubbing smooth wax onto the bottom of downhill skis.


c
Oiling the axles of a bicycle.


d
Getting a bicycle’s brakes wet.


e
Polishing a playground slide to make the surface smoother.


Friction produces
and
and can
.
things away.
I can…
●
identify some situations in which friction is helpful or not helpful
●
describe some ways in which friction can be changed
●
recall some effects of frictional forces.
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19
7
Investigating friction 1
Kc-2
Name
Class
Date
Your teacher may watch to see if you can:
●

follow instructions to carry out an investigation
record accurate results.
Hypothesis
The amount of friction depends on the force
pressing two surfaces together.
Prediction
1 Write a prediction for your investigation.
Method
A Attach the force meter to the block.
B Gently pull the block along the bench surface. Read the
force meter and write down the force needed to pull it.
C Pull the block twice more and write the results in the table.
D Put a 100 g mass on the block and repeat steps A to C.
Apparatus
●
force meter
●
wooden block with a hook
●
100 g masses
Take care that the block
does not fall off the bench.
E Repeat steps A to C with the other masses shown in the
results table.
Recording your results
Mass on block (g)
Force needed to pull block (N)
1st pull
2nd pull
Mean force (N)
3rd pull
0
100
200
300
400
500
2 Find the mean force for each mass. (Add up all three results, then divide your answer by 3.)
3 Show your results in a scatter graph.
Considering your results/conclusions
4 It took the biggest force to pull the block with
on it. It took the
on it.
smallest force to pull the block with
5 The
the mass on the block, the
the force pressing
pressing the block and the bench together. The
surfaces together, the
the force
the friction between them.
I can...
●
make and record careful observations
●
draw a conclusion.
●
calculate means
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20
7
Investigating friction 2
Kc-3
Your teacher may watch to see if you can:
●
carry out a careful and safe investigation.
Introduction
There are several different variables that could affect the amount of friction between two surfaces.
Plan an investigation to find out what effect one of these variables has:
● the material being dragged
● the area of the block being dragged
● the force pushing the two surfaces together
● the speed you pull the block.
Apparatus
Take care the block does not fall
off the edge of the bench.
Choose your apparatus from this list:
●
squares of different types of materials
●
force meter
●
wooden blocks of different sizes, each with a hook
●
100 g masses
●
4 drawing pins
Planning
1 Decide which variable you will investigate. Describe how you will carry out an experiment to
find out how this variable affects the friction between a block of wood and the bench.
2 Explain how you will make sure your investigation is fair.
3 Explain how you will make sure your results are as accurate as possible.
Recording your results
4 To get more accurate results, you should carry out each test three times and find the mean
force. Your table of results will look like this if you have tested different materials.
Material
Force needed to pull block (N)
1st pull
2nd pull
Mean force (N)
3rd pull
5 Carry out your tests and work out the mean force needed to pull the block each time.
6 Present your results in a bar chart or scatter graph. (Hint: the variable you changed should go
on the horizontal axis.)
Considering your results/conclusions
7 Write a conclusion for your experiment. Say how the factor you investigated affected friction.
Evaluation
8 Is there any way that you could have improved your investigation? Explain your ideas.
I can…
●
plan and carry out a safe investigation
●
present my data as a bar chart or scatter graph
●
draw a conclusion
●
evaluate my method.
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21
7
Friction – true or false?
Kc-4
The statements below are all about friction. Some are true, some are false, and some are
partly true.
● Cut out the statements. Work in a group to sort them into three piles, and make sure you know
why you have put each statement in a particular pile.
● Make a table in your book to show examples of useful friction, and examples of when friction is
not useful.
I can...
●
recall some effects of frictional forces
●
identify some situations in which friction is helpful or not helpful.
True
False
Partly true
A
B
Friction slows things down.
Cars need friction to keep moving.
C
D
Cars need friction to stop.
You could not walk without friction.
E
F
Friction is useful to gymnasts.
Matches light because of friction.
G
H
Friction is useful to ships.
Shoelaces stay tied up because of friction.
I
J
You could not pick up a cup of tea without
friction.
You could drink from a glass without friction.
K
L
Snow increases the friction between your
shoes and the ground.
Friction is useful in playgrounds.
M
N
Pencils do not need friction to write.
There is no friction when you are roller
skating.
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22
7
Hovercraft
Kc-5
A hovercraft does not need a road or
tracks because it rests on a cushion of
air that spreads its weight out. It can
move over bumpy fields, mud, sand,
snow or water, but it can’t be driven
over big waves or very rough ground.
Technically, a hovercraft flies, but as it
can never get more than a few
centimetres above the ground, people
tend to think of a hovercraft as
something between a land vehicle and
a boat.
Hovercraft have a lift fan, which pushes
air down beneath it. This air is held
beneath the vehicle by a flexible skirt,
and escapes from around the edges.
Hovercraft are propelled forwards by
large fans. These are a bit like the
propellers on some aeroplanes, but
they are mounted at the back. There
are rudders behind the fans that are
used to steer the hovercraft. These
change the direction of the air being
pushed out of the fan.
A hovercraft used by the Royal National Lifeboat Institution.
The RNLI use hovercraft in places like Morecambe Bay, where
there are large areas of mud and dangerous quicksand at low tide.
1 What will happen if the lift fan stops working?
2 Why is it much harder to pull a hovercraft along when its lift fans are switched off than when
they are switched on?
3 The axles of the lift fans and propellers need to be greased. Explain why they need to be
greased.
4 Most boats are propelled by small propellers in the water. Most land vehicles are moved by
making their wheels turn.
a
Suggest why hovercraft need to use fans to make them move.
b
Suggest why it is much harder to make a hovercraft change direction than a car.
5 a
b
Why does the material for the skirt need to be flexible?
What might happen if it was too flexible?
6 An aeroplane’s propellers do not have protection bars around them, but the thrust fans on
hovercraft are always put in metal cages. Suggest as many reasons for these differences as
you can.
7
Optional: Find out why the RNLI use hovercraft instead of lifeboats in places like
Morecambe Bay.
I can...
●
describe how a hovercraft works
●
explain some of the features of the design of a hovercraft.
The RNLI is a lifesaving charity, independent of Government.
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23
7
Name
1
Useful or not?
Kc-6
Class
Date
Look at the pictures below. Using a green pencil, circle the places where there is useful friction.
Using a red pencil, circle the places where friction is not useful.
2 On each picture, write down one way in which friction can be increased, and one way in which
it can be decreased.
A
B
Increase friction by
Increase friction by
Decrease friction by
Decrease friction by
C
D
Increase friction by
Increase friction by
Decrease friction by
Decrease friction by
I can…
●
identify situations in which friction is helpful or not helpful
●
describe how friction can be changed.
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24
7
Friction and sport
Kc-7
Name
Class
Date
1 Jack is going skiing.
Does he need high or low friction between his
skis and the snow?
Explain your answer.
2 Jill is climbing.
Where does she need high friction?
Explain your answer.
3 The drawing shows Samir riding his mountain bike.
a
Draw circles around the places on the drawing
where there should be a lot of friction.
Explain why there should be high friction in these
places.
b
Draw squares around the places where there should be low friction.
Explain why there should be low friction in these places.
c
How can Samir make sure the friction in these places is as low as possible?
I can...
●
identify situations in which friction is helpful or not helpful
●
explain why high or low friction is needed.
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25
7
Kc-8
Mountain bikes
Mountain bikes are used for riding on rough, stony tracks, mud or grass. Mountain bikers can go
up and down very steep hills. The drawing shows some of the ways in which a mountain bike is
different from a normal road bike. A mountain bike tends to be heavier than a road bike, unless it is
an expensive one made from special, light and strong materials.
1 Why is it an advantage for a mountain bike to have:
a
a lower cross-bar
b
suspension
c
stronger wheels and frame
d
fat tyres with a rough tread?
2 Suggest why a mountain bike is usually heavier than a road bike.
3 Mountain bikes are not as good as road bikes for cycling on roads. Give as many reasons for
this as you can.
4 The brakes on a normal road bike are on the wheel rims, right next to the tyres. Give one
reason why it is an advantage for a mountain bike to have brakes in the centre of the wheels.
5 The first bicycle with a chain joining the pedals to the rear wheel (the ‘safety bicycle’) was built
in 1885. Mountain biking only became popular in the 1980s.
a
Suggest why mountain biking has only become a popular sport in the last 20–30 years.
b
Optional: Cyclists can use ‘wet lube’ or ‘dry lube’ to lubricate their chains. Explain why
cyclists need to lubricate their chains, and find out the advantages and disadvantages of
each type of lubrication.
I can...
●
use information to make comparisons
●
explain why bikes are designed with differences.
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26
7
A curling question
Kc-9
Curling is a sport where teams take it in turns to push stones along a sheet of ice, aiming for a
target. The sport started in Scotland in the 1500s, when men would play it on frozen ponds or
lochs. Today curling is an Olympic sport.
Stones-R-Us manufactures and sells curling
stones. The normal stones have a weight of over
190 N. The company are interested in making
smaller stones so that children can learn the
sport. Their research department tested the
friction beneath different masses of stone to find
out if the mass of the stone affected the friction
between the stone and the ice. They did this by
measuring the force that was needed to keep
each stone moving at a steady speed along a
sheet of ice. The table shows their results.
Weight of
stone (N)
Force needed to move stone
at steady speed (N)
1st go
2nd go
3rd go
20
0.39
0.38
0.42
40
0.78
0.81
0.81
60
1.23
1.18
1.19
80
1.61
1.63
1.57
100
2.02
1.92
2.05
1 Draw up a table like this. Work out the mean of each set of three forces and complete the
second column of the table.
Weight of stone
(N)
Force needed to move stone at
steady speed (N)
20
2 Plot a scatter graph of the results on graph paper. Put the weight of the curling stones on the
horizontal axis, and the force needed to keep the stone moving on the vertical axis. Draw a line
of best fit on your graph. This is a straight line that goes through as many points as possible.
3 From your graph, find out the force needed to keep a stone moving if it has a mass of 7.0 kg.
4 Suggest why the research department tested each stone three times.
5 Which stone would go the furthest if they were all given exactly the same push to start them
off? Explain your answer.
2 N is quite a small force to keep a 100 N stone moving. The friction between the stones and the
ice is so low because there is usually some water on the surface of the ice.
6 Explain why water makes the friction low.
7
In curling, two members of the team sweep the ice in front of the stone. The amount of
sweeping they do can affect how far the stone travels. Suggest two different ways in which
sweeping the ice can help the stone to go further, and explain your answers.
I can...
●
work out means
●
present data as a scatter graph and draw a line of best fit
●
use data from a graph
●
explain ways of changing friction.
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27
7
Pressure
Kd-1
Name
Class
Date
1 Complete these sentences by crossing out the words that are wrong.
2
a
The snowshoes have a (large/small) area so
the pressure under them is (high/low) and the
person does not sink into the snow.
b
The crampons have spikes on the bottom.
The area of the spikes is (large/small) so the
pressure under them is (high/low). This helps
them to grip the ice.
c
The point of the drawing pin has a (large/small) area. The pressure
under the point is (high/low), which helps it to go into the wall.
d
The head of the drawing pin has a (large/small) area. The pressure
here is (high/low) so that it does not hurt your thumb.
e
You can increase the pressure by making the force (bigger/smaller)
and the area (bigger/smaller).
f
You can decrease the pressure by making the force (bigger/smaller)
and the area (bigger/smaller).
Fill in the gaps to calculate the pressure under the boots.
area of boots =
cm2
weight of man =
N
pressure = force ÷
.
=
÷
=
N/cm2
.
I can…
●
describe how the pressure depends on force and area
●
calculate pressure.
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28
7
Pressure on your body
Kd-2
Prediction
1 You put pressure on your feet when you are standing up.
a
How much more pressure do you think you put on your hands when you do a handstand?
b
How much more pressure do you think ballet dancers put on their toes when they stand on
the points of their toes?
Method
Apparatus
●
scales
●
calculator
●
tape measure
●
squared paper
Do not try balancing on parts
of your body in the laboratory!
A Find your weight in newtons. If you only have scales that show
kilograms, multiply your answer by 10 to give newtons (e.g. a 65 kg
mass gives a weight of 650 N).
B Measure the area of as many parts of your body as you think you could balance on by drawing
around them on squared paper and counting the squares. Try your head, feet, tiptoes and
hands. You could also work out how much pressure is on you when you sit down.
Recording your results
2 Copy this table for your results.
Part of body
3
Weight of body (N)
Area of part of body
(cm2)
Pressure on body
part (N/cm2)
Calculate the pressure for each part of your body using the formula
pressure = force ÷ area
4
Record your results in a bar chart.
Considering your results/conclusions
5 Copy and complete these sentences by filling in the blanks and choosing the correct words
from the brackets.
a
The part of my body that would have the greatest pressure on it is
b
If I balance on one foot instead of two the pressure is (doubled/halved).
c
When I do a handstand the pressure on my hands is (bigger/smaller) than the pressure
when I am standing on my feet.
.
I can…
●
measure areas
●
calculate pressures
●
present my results as a bar chart.
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29
7
Different units
Kd-3
Area of Wales
20 779 km2
Volume of an
Olympic swimming
pool
2500 m3
Height of a doubledecker bus
about 4.5 m high
Length of a football
field
90–120 m
Facts and figures reported in the press or on TV often include comparisons to try to help us to
understand the size of something. You can think of ‘the area of Wales’ or ‘the height of a doubledecker bus’ as different units.
1 Which of the ‘units’ above would you use for the following news items?
a
the size of a new tower block
b
the amount of water leaking from a burst water main
c
the queue to buy cheap tickets for a concert
d
the sea covered by an oil spill.
2 Here are two different ways of reporting an oil spill.
a
Which headline provides the most accurate value for the area of sea covered?
b
Which headline gives you the best idea of the size of the spill?
3 The following facts and figures were reported in a paper. Rewrite them using the ‘units’
given above.
4
a
The new Shard skyscraper in London is 304 metres tall.
b
The new riverside park is 500 m long.
c
It is estimated that 100 000 m3 of oil was spilled from the wrecked tanker.
a
What are the advantages of using these unusual units?
b
Suggest what problems there may be with giving information only in terms of these
units.
c
Explain why scientists all use SI units.
I can…
●
convert between different units.
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30
7
Wintry sums
Kd-4
Snowshoes can help you to walk on soft snow without sinking in. Most snowshoes have little
spikes underneath to help you to walk on icy ground.
The formula for calculating pressure is:
pressure =
force
area
Use units of N/cm2 for all the pressures you calculate on this worksheet.
1 Fran is wearing boots. Her weight (including her clothes and boots) is 500 N. The area of the
sole of one of Fran’s boots is 170 cm2.
a
What is the pressure under Fran when she is standing on one foot?
b
What is the pressure under Fran’s boots when she is standing on both feet?
c
Which of these two pressures is the most important when you are thinking about whether or
not she will sink as she walks in snow? Explain your answer.
2 Fran wants to buy a pair of snowshoes. She has been told that the area of each snowshoe
should be about 14 cm2 for every 10 N of her weight. The table shows some of the snowshoes
she could buy.
a
b
What area should each of Fran’s new
snowshoes have? You can ignore the mass of
the snowshoes because that is the same for
each pair.
Snowshoe
What pressure will Fran put on the snow when
she is standing on one snowshoe?
Area (cm2)
A
300
B
432
C
770
D
1040
c
Which pair of snowshoes should Fran buy? Explain your answer.
d
Suggest why it is not a good idea for Fran to buy a pair that is bigger than she needs.
3 Fran’s new snowshoes have little spikes underneath. The total area of the spikes on each
snowshoe is 1.5 cm2.
4
a
What pressure does Fran put on the ground with one foot when only the spikes are
touching the ground?
b
Why is this high pressure useful?
Fran also has a pair of crampons. The total area of all the spikes on each crampon is 0.1 cm2.
How can you tell without doing any calculations that Fran will put more pressure on a sheet of
ice with the spikes on her crampons than with the spikes on her snowshoes?
I can…
●
calculate pressures.
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31
7
A winter walk 1
Kd-5
Name
Class
Date
Hi Mum
We tried the snowshoes today. They are big things we strap to our boots and they stop us
sinking in the snow. Some of the other people didn’t have them and they sank in up to their
knees!
We went right to the top of the mountain. The snow was really hard near the top, but luckily
the snowshoes have little spikes underneath so we didn’t slip at all.
There were some people near the top trying to climb up an icy wall. They had spikes strapped
to their boots, and ice axes that they dug into the ice. It looked very hard! There were some
other people skiing down the hill.
We had lunch near the top. It was so cold I had to use my knife to cut the chocolate. It was
nearly dark when we got back to the village. A boy had fallen through the ice on the pond.
A man put a ladder down on the ice and crawled out along it. There was a huge crowd! They all
gave a cheer when he pulled the boy out.
Love from Alex
1
a
Underline all the parts of the letter that show the pressure being made less.
b
Put a box around all the parts that show the pressure being increased.
2 Underline the correct words in the brackets.
a
In the parts underlined, the pressure is reduced by making the (area bigger/area
smaller/force smaller).
b
In the parts with boxes around, the pressure is made bigger by making the (area
bigger/area smaller/force smaller).
3 Look at the drawing of the snowshoes. Draw circles around the parts that make the pressure
higher under them.
4 How did a knife help Alex to cut the chocolate?
5 How did the ladder help the man to crawl on the ice without falling in?
I can…
●
describe how pressure depends on force and area
●
describe some real-life situations involving high and low pressure.
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32
7
Kd-6
A winter walk 2
Hi Janie
We had a great day out today – we tried the snowshoes. We had a good laugh at the people
trying to walk in the snow without them – some of them were up to their knees! Some kids
were sledging – we might have a go at that tomorrow. Someone passed us on skis, going really
fast. It looked great fun!
We went right to the top of the mountain. The snow was really hard near the top – luckily the
snowshoes have little spikes underneath so we didn’t slip at all.
There was a group of people near the top with an instructor. Some of them were trying to
climb up an icy wall. They had spikes strapped to their boots, and ice axes that they dug into
the ice. It looked too much like hard work to me. The others were sliding down the hill and
then trying to stop themselves by digging their ice axes in. That looked like fun – some of
them even set off head first!
We had lunch near the top. It was so cold I had to use my knife to cut the chocolate. It was
nearly dark when we got back to the village. Some kid had tried skating on the pond and had
fallen in. When we got there a man had put a ladder down on the ice and he was crawling out
along it. There was a huge crowd! They all gave him a cheer when he pulled the kid out.
Anyway – time for dinner now. See you soon!
Alex
1 Snowshoes can reduce or increase the pressure beneath them.
a
Explain why this is useful. (Hint: think about the different surfaces that Alex walked on.)
b
Explain how the snowshoes can reduce or increase the pressure.
2 The ice climbers are using two different pieces of equipment. How do these help them to climb
on hard ice? Use ideas about pressure in your answer.
3 Why did the people sliding down the hill need to use ice axes to stop themselves?
4 Why did the man rescuing the boy from the pond use a ladder? Explain in as much detail as
you can.
5 Find two other events in the letter that show pressure being increased or decreased.
6 How do skis help you to go fast downhill?
I can…
●
describe how pressure depends on force and area
●
explain applications of pressure in different situations.
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33
7
Kd-7
Tyres and pressures
Pressure, force and area are related by a formula. The formula can
be written in different ways, depending on which quantity you need
to calculate. Choose the formula that has the quantity you want to
calculate on the left-hand side of the equals sign.
pressure = force ÷ area
force = pressure  area
area = force ÷ pressure
1 Pa = 1 N/m2
1 m2 = 10 000 cm2
The weight of a bicycle is supported by the pressure of the air inside the tyres. If the tyres are
pumped up hard there is a small area of the tyre in contact with the ground. If the air in the tyres is
at a low pressure the tyres are easy to squash and the area of the tyre in contact with the ground
gets bigger. The total area of the tyres in contact with the ground can be calculated from the
pressure of the air in the tyres and the total weight of the bike and its rider.
Sam has three different bicycles. Sam’s weight is 700 N.
Road bike
weight: 90 N
tyre pressure: 760 kPa
Mountain bike
weight: 130 N
tyre pressure: 170 kPa
Touring bike:
weight (loaded): ?
tyre pressure: 550 kPa
1 Calculate the total tyre area in contact with the ground for:
a
Sam on his road bike.
b
Sam on his mountain bike.
2
Explain why the road bike and mountain bike have very different tyre pressures.
3
When Sam is on his touring bike the tyre area in contact with the ground is 0.0015 m2.
Calculate the total weight of Sam and his bike.
This is a quad bike. Farmers often use them to help them to
carry animals or travel across muddy fields. Its weight
(including farmer and dog!) is 4000 N and the total area of tyres
in contact with the ground is 0.083 m2.
An off-road vehicle has a weight of 26 000 N (including the
driver) and the total area of tyres in contact with the ground is
0.113 m2.
4
Which vehicle will sink deepest into mud? Explain your
answer (you will need to carry out some calculations to help
you to explain).
I can…
●
explain applications of pressure in different situations
●
use the formula relating force, pressure and area.
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34
7
Ke-1
Name
1
Balanced and
unbalanced forces
Class
Date
Join the boxes to complete the sentences. Some sentences have more than one ending.
…can make it speed up.
An object has balanced forces on it…
…can change the direction it is moving
Unbalanced forces on an object…
…when there are two forces of the same
size in opposite directions.
Balanced forces on a stationary object…
…will not change its speed or direction.
Balanced forces on a moving object…
…will not make it move.
…can make it slow down.
2 The drawings show a racing sled. Some of the force arrows have been drawn for you. Draw in
the missing arrows and label them as necessary. Remember that the length of the arrow shows
the size of the force.
a
constant speed
b
speeding up
c
slowing down
I can…
●
identify balanced and unbalanced forces
●
explain the effects of balanced and unbalanced forces.
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35
7
What will happen?
Ke-2
There are several different forces on a
diver.
1 Describe what will happen to the diver
in each situation below. Look very
carefully at the sizes of the force arrows
on the diagrams.
2 Think of a situation of your own that
involves different forces on an object.
Draw a diagram including force arrows,
and explain how the forces will affect
the movement of the object.
A
B
C
D
E
F
I can…
●
identify balanced and unbalanced forces
●
describe the effects of balanced and unbalanced forces.
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36
7
Ke-3
Forces and movement
Aristotle (374–322 BCE) was a famous Greek
philosopher (thinker). He was one of the first people
to think in a scientific way about forces. One of his
theories was that moving things kept moving as long
as there was a force on them. This idea seems
obvious when you think about things like carts.
Aristotle’s ideas relied on thinking about
observations; he did not carry out investigations to
test his theories.
Things that were thrown, like arrows, were a little
harder to explain.
Many other scientists studied forces and
movement. One of the most famous was
Galileo Galilei (1564–1642). Galileo knew
about Aristotle’s ideas, and he decided to test
them. He carried out a lot of experiments to
study how objects moved on different surfaces,
and realised that there was a force that tried to
slow things down. This is the force we call
friction. He suggested that if you could reduce
friction to zero, an object would keep moving
for ever.
1
a
What was Aristotle’s idea about forces and moving objects?
b
What was Galileo’s idea?
2 a
How did Aristotle arrive at his ideas?
b
How did Galileo arrive at his ideas?
c
Which method is closest to the method that scientists use today?
Page 1 of 2
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37
7
Ke-3
Forces and movement
3 You are cycling at a steady speed along a level road. You need to keep pedalling to keep
moving at a steady speed.
a
How would Aristotle explain the fact that you need to keep pedalling?
b
How would Galileo explain it?
4 You stop pedalling.
a
What happens to the speed of the bicycle?
b
Can Aristotle’s idea explain this? If so, how?
c
Can Galileo’s idea explain this? If so, how?
I can...
●
recall that ideas about forces and movement have changed
●
describe how evidence can be used to change ideas
●
describe how friction forces affect movement.
Page 2 of 2
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38
7
Modelling forces
Ke-4
We can use arrows to show the direction and size of a force. The arrows are acting as a model to
help us to think about forces.
The drawings all show the same cyclist moving at 5 m/s.
A
B
C
D
1
What does B tell you that A does not?
2
What does C tell you that A and B do not?
3
What does D tell you that the other diagrams do not?
4 Explain which diagram is best if:
5
a
you want to work out what will happen to the speed of the bike.
b
you want to know about the different kinds of force acting on the bike.
c
you want to work out how you could make the bike go faster.
Look at your answers to question 4. Describe (or draw) your own combination of arrows that
you think would be best for each purpose.
I can…
●
Evaluate the usefulness of different ways of representing forces.
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39
7
Ke-5
Springs and bungee jumps
The cards and labels below show what happens when you use a force meter to weigh an object,
and when someone does a bungee jump. A bungee jumper bounces up and down a few times
before they stop moving – these cards only show what happens as far as the bottom of the first fall.
1 Cut out the cards and arrange them to explain how the forces affect:
a
the force meter
b
a bungee jumper.
Check your arrangement with your teacher before sticking them into your book.
I can…
●
compare the size of different forces
●
explain the effects of balanced and unbalanced forces.
A
B
C
D
E
F
As the spring stretches, it
produces a bigger force.
When the spring has stretched
far enough, the force from the
spring is equal to the weight of
the object.
The object has just been put
on the force meter. The spring
has just started to stretch.
G
H
I
The downwards force is bigger The forces are balanced so
than the upwards force, so the the spring does not stretch
spring gets longer.
any further. The force meter is
showing the weight of the
object.
The downwards force is still
bigger than the upwards force,
so the spring carries on
stretching.
Page 1 of 2
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40
7
Ke-5
Springs and bungee jumps
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
The person is
falling faster so
the air resistance
is greater. They
haven’t fallen far
enough yet to
stretch the
bungee.
The downwards
force is much
bigger than the
upwards force,
so they fall faster
and faster.
The forces on the
person are
balanced.
Because they are
already moving,
they continue to
move at the same
speed.
The downwards
force is still bigger
than the upwards
force, so they are
still gaining speed
downwards, but
not as much as
before.
The upwards
force will make
the person slow
down and stop,
and will then
make them start
to move upwards
again.
p
q
r
s
t
The bungee has
stretched even
more, so the total
upwards force is
bigger than the
downwards
force.
The person has
just jumped.
Their weight is
pulling them
downwards.
They are not
moving fast, so
there is a very
small force from
air resistance.
The bungee has
just begun to
stretch. It starts
to exert an
upwards force on
the jumper.
There is also a
force from air
resistance.
The combined
upwards forces
are not quite as
big as the
weight. The
person is still
gaining speed
downwards, but
not very much.
The bungee has
stretched enough
so that the force
from the bungee
and the air
resistance
combined are the
same size as the
weight.
Page 2 of 2
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41
7
Changing speed 1
Ke-6
Name
Class
Date
1 Look at the drawings of the cyclists.
a
Who is moving the fastest?
b
Who is not moving at all?
2 Bev will continue to move at 7 m/s. How can you tell this from the drawing?
3 What will happen to Al’s speed?
Explain your answer.
4 What will happen to Charlie’s speed?
Explain your answer.
5 What will happen to Dinesh’s speed?
Explain your answer.
6 What will happen to Ellie’s speed?
Explain your answer.
7 What is causing the forces in the drawing that are slowing the cyclists down?
I can…
●
identify balanced and unbalanced forces
●
explain the effects of balanced and unbalanced forces.
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42
7
Ke-7
Changing speed 2
1 Look at the drawing of the cyclists.
What will happen to the speed of each person? Explain your answers.
2
If they all carry on cycling with the same force as in the drawing, who will be moving the fastest
in 5 minutes’ time? Explain your answer.
These drawings show Fran abseiling. She is using friction
to control how fast she moves down the rope.
3
a
What is the force that is pulling Fran down in
drawing A?
b
Does this force change in the situations shown in
drawings B and C? Explain your answer.
c
What is stopping this force making Fran move down
in drawing A?
4
Are the forces on Fran balanced or unbalanced in each
drawing? Explain your answers.
5
Describe two examples in everyday life of:
a
balanced forces on a stationary object
b
balanced forces on a moving object.
I can…
●
identify balanced and unbalanced forces
●
explain the effects of balanced and unbalanced forces.
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43
7
Ke-8
Climbing ropes
Rock climbers and mountaineers use ropes to stop them getting hurt if they fall, but did you know
that climbing ropes are stretchy?
Think about a spring like this chest expander. It is
quite easy to stretch it a little way, but it takes a
much bigger force to stretch it a long way. The
amount of force from the spring depends on how
far it has been stretched.
The same thing happens with climbing ropes.
1 What force or forces are acting on the falling climber in picture B?
2
3
a
What forces are acting on the climber in C?
b
Are the forces balanced or unbalanced?
c
What will happen to the falling speed of the climber?
Are the forces balanced or unbalanced in D?
4 a
5
Will the climber fall further than the point she has already reached in D? Explain your
answer.
b
What will happen to the force from the rope if she falls further?
c
What effect will this have on her speed?
a
If she had a more stretchy rope than the one shown, would she fall further or less far?
b
What would happen if the rope was too stretchy?
6 In the example above, the force on the climber from the rope increases gradually.
a
What would happen if the rope was not stretchy?
b
What would it feel like if a non-stretchy rope stopped her fall?
I can…
●
explain the effects of balanced and unbalanced forces in unfamiliar situations.
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44