Physics: 1. Measurement, equipment and units
OP1
OP2
Syllabus
Measure length, mass, time and temperature, and perform simple calculations based on these to find the
derived quantities: area, volume, density.
Understand that units of measurement follow the SI system.
Measure mass and volume of a variety of solids and liquids.
Student Notes
There are literally hundreds of different units for some quantities like length and mass.
How different units of length can you think of?
It is important for scientists that everybody is using the same units.
Can you say why?
Scientists use units called S.I. Units
S.I. stands for Système International d'unités ; it is in french because it was the French who first promoted this system
(you don’t need to know this).
What do you think Système International d'unités means ?
S.I. units
Symbol
Equipment
Length
metres
Mass
Kilograms
Time
seconds
m
Metre stick,
Opisometer
kg
Electronic
balance
s
Clock,
stopwatch
Temperature
Degrees Celsius
0
C
Thermometer
Area
Metres
squared
m2
Volume
Metres
cubed
m3
Speed
metres per
second
m/s
Other commonly-used units:
Mass: grams (g)
Area: centimetres squared (cm2)
Volume: centimetres cubed (cm3)
1 litre = 1000 cm3
Area of a regular object = length × width
Volume of a regular object = length × width × height
Instruments used to measure the volume of a liquid
1. Graduated cylinder
2. Pipette
3. Burette
To find the volume of a small stone
Carefully drop the stone into a graduated cylinder which already has water in it and note the increase in volume of
water.
To find the volume of a large stone
Carefully drop the stone into an overflow can which is already full to the top with water and note the amount of water
that it pushes out by placing a graduated cylinder under the spout of the overflow can.
To find the mass of a solid object
The mass of an object can be found by weighing it using an electronic balance (commonly known as a weighingscale).
To find the mass of a liquid
First find the mass of an empty container, then pour the water into it and find the new mass.
Subtract to find the mass of the liquid.
1
Exam Questions
1. [2006 OL]
Find the area of the rectangle drawn on the right using the measurements given.
In what unit is the area measured?
2. [2007 OL]
(i) What is the name the piece of equipment shown on the right?
(ii) Give one use of this piece of equipment.
3. [2007]
(i) Name the item of laboratory equipment shown in the diagram.
(ii) Name a second item of laboratory equipment which enables more accurate measurements of volume to be
made.
4. [2006 OL] [2009 OL]
(i) The diagram shows a piece of equipment, labelled A, containing water. Name A.
(ii) A stone was then added and a new volume was recorded as shown in B.
What was the volume of the stone in cm3?
5. [2008 OL]
Name and give one use for the piece of equipment shown in the diagram.
Answer
Thermometer; it is used to measure temperature
6. [2008 OL, 2006 OL]
(i) Name the piece of equipment drawn on the right.
(ii) Give one use for this piece of equipment.
7. [2008]
(i) Give one safety precaution taken by the pupil, shown in the photograph, while doing
an experiment in a school laboratory.
(ii) Describe a precaution, not shown in the photograph that you would take when heating
a substance in a test tube in a school laboratory.
8. [2009]
Name any two items of laboratory equipment shown in the diagram.
2
Other Test Questions
1. What is the unit of (i) Length, (ii) Time, (iii) Mass, (iv) Area, (v) Volume?
2. What instrument would you use to measure (i) the length of a curved line, (ii) diameter of a marble?
3. Name two instruments used to measure weight.
4. What is an opisometer used for?
5. Name two instruments used to measure mass.
6. Name two instruments used to measure volume of a liquid.
7. Name an instrument used to measure the altitude of a mountain climber.
8. Name an instrument used to measure the distance by road between two locations on a map.
3
Physics: 2. Density
OP2
Syllabus
Measure mass and volume of a variety of solids and liquids and hence determine their densities.
Student Notes
We learned how to measure the mass and volume of objects in a previous chapter. To measure density we simply use
the following formula:
Mass
The unit of density is the kg/m3 (pronounced “kilogram per metre cubed”) or g/cm3
4
Density × Volume
Mass, Volume and Density: Exam questions
1. [2008 OL]
(i) Complete the equation in the box below using the words on the right.
Density =
(ii) If the mass of a stone is 20 g and the volume of the stone is 10 cm3, find the density of the stone.
2.
[2007 OL]
A block of metal has the measurements shown on the right.
The mass of the metal block is 21 g.
(i) Write the letter V beside the value of the volume of the block.
(ii) Write the letter D beside the value of the density of the block.
3. [2009 OL]
The mass of a metal block is 14.7 g. It has a volume of 7 cm3.
(i) Name the instrument you would use in the laboratory to find the mass of the
block.
(ii) Write the letter D beside the value of of the density of the block.
(iii) Write the letter U beside the unit used to measure the density.
MASS
VOLUME
8 cm3
10 cm3
2.1 g cm–3
210 g cm–3
2.1
102.9
cm3
g/cm3
4. [2009]
A pupil measured the volume of a potato using the items of laboratory equipment, labelled A and B as shown in
the diagram.
(i) Name the items labelled A and B.
(ii) The potato had mass 175 g and volume 125 cm3.
Calculate the density of the potato.
Give the units of density with your answer.
(iii) Why did the potato sink in the water?
5. [2007]
Ice floats on water but ice sinks in ethanol (an alcohol).
Use this information to compare the density of ice with
(i) the density of water;
(ii) the density of ethanol.
5
Other Test Questions
1. What is meant by the term ‘density’?
2. What is the formula used to calculate the density of an object?
3. What are the units of density?
4. Draw a diagram of the apparatus used to measure the density of an irregular-shaped object?
5. Describe with the aid of a diagram an experiment to measure the density of an irregular object.
6. Describe with the aid of a diagram an experiment to measure the density of a liquid.
7. A stone has a mass of 120 g and a volume of 20 cm3, what is the density of the stone?
8. The density of Iron is 8 g/cm3. Calculate the mass of 6 cm3 of Iron.
9. What is the density of an object which has a mass of 20 kg and whose volume is 4 m3?
10. Draw a diagram of the apparatus used to measure the density of an irregular-shaped object?
11. A student measured the density of a number of substances. The results are shown in the table below.
Substance
Density (g/cm3)
Cork
0.3
Polystyrene
0.03
Water
1.0
Paraffin Oil
0.7
Rubber
1.1
Identify two substances that would float in paraffin oil.
12. Why can a solid like ice float on water?
6
Physics: 3. Velocity & Acceleration
Syllabus
OP1 Perform simple calculations based on speed, velocity, and acceleration
Student Notes
Speed
Speed = distance ÷ by time
The unit of speed is the metre per second (m/s).
Distance
Speed × Time
Velocity
Velocity is much the same as speed, except when we talk about velocity we usually include a direction, e.g. the
velocity of a car is 10 m/s due East.
The slope of a distance-time graph corresponds to the velocity of the object.
Acceleration
Acceleration = velocity ÷ by time
The unit of acceleration is the metre per second squared (m/s2).
Consider an object which is speeding up as it is moving. Its velocity after one, two, three and four seconds is given in
the following table:
Time
Velocity
1 second
10 m/s
2 seconds
20 m/s
3 seconds
30 m/s
We can see that with every second that passes the velocity increases by 10 m/s.
Alternative ways of writing this are
 the velocity increases by 10 m/s per second,
 the velocity increases by or 10 (m/s)/s
 the velocity increases by 10 m/s2
Instead of saying that ‘the velocity increases by 10 m/s per second’, we simply say that ‘the acceleration is 10 m/s2’.
Problem: A sports car can go from 0 to 300 m/s in 10 seconds. Calculate the acceleration
Answer:
The slope of a speed-time graph corresponds to the acceleration of the object.
7
Exam Questions
1. [2009]
Define velocity.
2. [2007 OL]
The speed of a car is 15 m s–1.
(i) In the table write the letter D beside the distance the car will travel in 5 seconds.
(ii) Write the letter F beside the word that describes what happens when the speed of a car
increases.
3. [2009 OL]
(i) A cyclist moves 20 metres along a track in 4 seconds.
In the table write the letter S beside the speed of the cyclist.
(ii) Write the letter D beside the distance the cyclist will travel in 2 seconds.
4. [2008 OL]
A cyclist moved along a track.
The distance travelled by the cyclist was measured every 2 seconds.
The data collected is presented in the table below.
Distance travelled (m)
Time (s)
0
0
10 20
2 4
3m
75 m
Acceleration
Force
5 m/s
80 m/s
10 m
40 m
30 40
6 8
(i) Use this data to draw a graph of distance travelled (y-axis) against time (x-axis) using the grid provided below.
(ii) Use the graph to estimate the distance travelled by the cyclist in 5 seconds.
(iii) Calculate the speed of the cyclist in m s–1 (m/s).
8
5. [2009]
A stone was dropped from the top of a tall cliff. The stones approximate velocity was measured each second as it
fell. The data collected during this experiment is given in the graph.
Use data from the graph to estimate the acceleration of the stone as it fell. Give the units of acceleration with your
answer.
Other Test Questions
1. Define Velocity.
2. Define Acceleration.
3. What is the formula for calculating speed?
4. What is the unit of speed?
5. Calculate the velocity of a swimmer who swims 100 m in 20 secs.
6. Calculate the velocity of a teacher who runs 150 m in 30 seconds.
7. How long does it take a girl to travel 1000 m, if her speed is 2 m/s?
8. How long does it take a person to travel 1000 m, if their velocity is 20 m/s?
9. What are the units of acceleration?
10. One car can go from 0 to 100 m/s in 10 seconds while another car which can go from 100 m/s to 150 m/s in 3
seconds. Which car has the greater acceleration?
9
Physics: 4. Force
OP4
Syllabus
Understand the concept of force, recall that the newton is the unit of force, and describe forces and their
effects
OP5
Investigate examples of friction and the effect of lubrication
OP6
Investigate the relationship between the extension of a spring and the applied force
OP7
Understand that weight is the force of gravity and that weight varies with location; recall that mass in
kilograms multiplied by 10 is approximately equal to weight in newtons on the surface of the earth.
Student Notes
A force is something that causes an object to change velocity or accelerate.
The newton (symbol N) is the unit of force.
Forces can be measured using a spring-balance (the proper name is a newton-meter).
Friction
Friction is a force that opposes motion between two objects in contact.
Friction can be a nuisance (e.g. it slows things down when you don’t want it to when driving a car or riding a bike).
Friction can also be useful (e.g. brakes on a bike, and to enable us to walk).
Experiment: To demonstrate friction and how a lubricant can be used to reduced friction.
Attach a spring balance to a wooden block and use it to pull the block over the bench. Note the reading on the springbalance.
Now put some oil or grease under the block and repeat. Notice that the force required to pull the block is much less.
Weight and Mass
Mass is a measure of the amount of matter (“stuff” )in something.
The weight of an object is a measure of the gravitational pull on it.
Weight is a force (due to gravity)
The mass of an object doesn’t change from one place to the next because it still has the name amount of stuff inside
(the same number of atoms), but the weight of the object will be much less on a planet smaller than Earth (or on the
moon) while it will weigh much more (it will be much ‘heavier’) on a bigger planet. In fact if you could go to one of
the bigger planets you would not even be able to stand up because you weigh so much!
Maths Problems
Weight (in newtons) = Mass (in kilograms) × 10
e.g. a student of mass 60 kg has a weight of 600 N.
Note: There are 1000 grams in a kilogram (kg).
10
Hooke’s Law
The extension of a stretched string depends on the force that is stretching it.
Experiment: To investigate the relationship between the extension of a spring and the force that is
stretching it.
1. Use a newton-meter to stretch a spring and note the extension and the force used.
2. Repeat for lot of different forces.
3. Plot a graph of force used against extension.
4. Result: You should get the graph on a straight line.
5. Conclusion: The graph of a straight line shows that the extension increases at a constant rate with the
applied force.
Exam questions
1. [2007 OL]
Different units are used to measure different physical quantities.
(i) In the table on the right write the letter L beside the unit of length.
(ii) Write the letter W beside the unit of weight.
Metre
Newton
Joule
2. [2009 OL]
Friction can be useful when driving a car.
(i) Name one way in which friction is useful when driving a car.
(ii) Name one possible way to reduce friction.
3. [2006 OL]
Friction is an example of a force.
(i) Give another example of a force.
(ii) Give one way to reduce friction.
(iii) After what scientist is the unit of force named?
4. [2008]
The globular cluster shown is a group of stars (like a small galaxy).
Gravity is the force that holds the stars together in this formation.
Give two effects that gravity has on your everyday life.
5. [2009]
(i) A stone was dropped from the top of a tall cliff. Name the force that causes the stone to fall downwards.
(ii) The stone had a mass of 2 kg. What was the weight of the stone on earth? Give the unit.
6. [2006]
A pupil measured the weight of an apple of mass 0.2 kg using a spring balance and got a reading of
2 N. Distinguish between weight and mass.
7. [2006]
State Hooke’s law.{This isn’t on the syllabus and shouldn’t have got asked, so presumably won’t
appear again – but you never know}
Robert Hooke (1635-1703) made a number of discoveries including the effect of force on elastic
bodies now known as Hooke’s law.
11
8. [2006 OL]
A student carried out an investigation to examine the relationship between the extension (increase in length) of a
spring and the force applied to it.
The diagram shows the apparatus used.
The table shows the data collected by the student.
Force (N)
Extension (cm)
0 2
0 4
4
8
6 8
12 16
(i) Describe how the student could have taken any one of these measurements.
(ii) Draw a graph of the extension (y-axis) against the force in the grid provided on the right.
(iii) What force results in a 6 cm extension of the spring?
9.
12
9. [2006]
A student was given a box of identical springs and asked to analyse them so that they could be used
as newton meters. The student performed an experiment, using the apparatus shown in the diagram,
on one of the springs.
In the experiment the student measured the increase in length of the spring caused by a number of
weights. The spring was tested to destruction (that is weights were added until the spring was
damaged).
The data from the experiment is given in the table.
Weight (N)
Extension (cm)
0.0 0.4
0.0 2.0
0.8 1.2
4.0 6.0
1.6 2.0
8.0 8.5
2.4
8.6
(i) Plot a graph of extension (increase in length – y-axis) against weight (x-axis) in the grid provided.
(ii) Use the graph to find the weight that would produce an extension of 5 cm in the spring.
(iii) Study your graph carefully.
The spring obeys Hooke’s law for the earlier extensions and then when the spring becomes damaged it does not
appear to do so.
Estimate, from your graph, the weight after the addition of which the law seems no longer to apply.
13
10. [2009 OL]
A student investigated the relationship between
the extension of a spring and the force applied to
it.
The equipment shown in the diagram was used.
The data collected is shown in the table.
Force (N)
Extension (cm)
0
0
2
4
4
8
6 11. 8
12 12. 16
The student then drew the graph shown below.
Answer the questions that follow about this
investigation.
(i) Name an instrument used to measure the force in
this investigation.
(ii) Describe how the student could have measured the
extension of the spring.
(iii) What conclusion would you draw from this
investigation?
Other Test Questions
1. What is meant by the term ‘force’?
2. What is meant by the term ‘friction’?
3. Give an example of how friction can be useful on a bicycle?
4. Give an example of how friction can be a nuisance on a bicycle?
5. How might a cyclist reduce friction?
6. Give another example of how friction can be useful.
7. Give another example of how friction can be a nuisance.
8. Describe how you would investigate the effectiveness of two different lubricants. Include reference to a control.
Give three ways of making sure that you carry out a fair test.
9. What is meant by the term ‘mass’? What is the unit of mass?
10. What is meant by the term ‘weight’? What is the unit of weight?
11. Name two instruments used to measure weight.
12. Calculate the weight (in Newtons) of a bag of sugar, which has a mass of 500 grams.
13. A man has a mass of 100 kg. What is his weight?
14. Would the man weigh less, more or the same on the moon?
15. Why does the man have a different weight on the moon?
16. What will be the mass of the man on the moon?
17. How would you be affected if your weight suddenly doubled?
14