igcse notes physics numbered-140205153241-phpapp01

8/20/2019 Igcse Notes Physics Numbered-140205153241-Phpapp01

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Contents

Topic Page Number

Topic 1 General Physics 2 Past Paper Questions 26

Topic 2 Thermal Physics 70 Past Paper Questions 83Topic 3 Waves 108 Past Paper Questions 120

Topic 4 Electricity & Magnetism 146 Past Paper Questions 173Topic 5 Atomic Physics 214

Past Paper Questions 221

Appendix

Syllabus 234

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Topic 1:General Physics

Length

• Length is a distance measurement and its SI unit isthe metre ! ! ".

• Length is usually measured with a rule, a tape or atrundle wheel.

• Small lengths are measured with a micrometer or

callipers where a greater precision is available.

• In certain circumstances, averag ! lengths can befound be measuring a number of distances togetherthen dividing by the number of objects eg a ream ofpaper.

Time

• Time is usually measured with a stopclock. Humantiming is not precise because of reaction times.

• The SI unit for time is seconds ! s ".

• For repeated events, an averag ! time can be foundby measuring a number of repeats then dividing bythe number of cycles eg. a pendulum.

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Speed

• Speed tells us how fast something is moving.

• It is measured in m/s.

• Average speed is calculated using:

Average Speed (m s) =Distance moved (m)

time taken (s)

Examples• A sprinter runs 100 ! in 10 s. Calculate his average speed.

• A bird flies 60 ! in 5 s. Calculate its average speed.

• Pupils measured their times taken to travel di# erentdistances doing various exercises. Their results are recordedin the table. Complete the table.

Exercise Distance ! ! " Time ! s " Speed ! m/s "

Running 70 12

Walking 10 35

Hopping 50 110

Acceleration• Acceleration tells us how quickly something is changing

its speed.

• It is measured in m/s 2.

• Acceleration is calculated using:

Average Acceleration (m s2) =

Change in speed ( m s )

time taken (s)

Example:

• A motorbike goes from 10 m/s to 35 m/s in 8 s. Calculatehis acceleration

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Distance/time graphs

• A Distance/time graph is a way of representingmotion.

time

distance

stationary Constant speed ! fast "

Constant speed ! slow "

Acceleration

Calculations with distance/ time graphs

• Speed is given by the gradient of the distance/time graph.

Distance/time graph questions

• Describe the motion of the following bodies:

t

d! a "

t

d

! b "

t

d

! c "

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Distance/Time Graphquestions

• Calculate the speeds of the car and the bikebelow:

Car Bike

0

125

250

375

500

0 5 10 15 20 25

D i s t a n c e ( m )

Time (s)

Speed/time graphs

• A Speed/time graph is an alternative wayof representing motion.

time

speed

Constant speed

Rapid acceleration

Gradual acceleration

Non$Uniform Acceleration

Stationary

Calculations with speed/time graphs

• Acceleration is given by the gradient of the speed/ time graph.

• Distance is given by the Area under the speed/time graph.

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Speed/time graph questions

• Describe the motion of the followingbodies:

t

v ! a "

t

v

! b "

t

v

! c "

Speed/time calculation.

• ! a " Find the acceleration of the bike in the first 10 s.

• ! b " Find the distance moved by the bike in the first 20 s.

0

3.75

7.50

11.25

15.00

0 5 10 15 20

Motion of a bike

S p e e d ( m

/ s )

time (s)

The Ticker$ Timer

• The ticker$timer runs at 50Hz. It puts 50 dots onthe tape every second.

• If the tape moves quickly, the dots are widelyspaced.

• If the tape moves slowly, the dots are close

Ticker Timer

Ticker Tape

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Ticker TapeSlow moving ticker-tape

Fast moving ticker-tape

Charts

• By cutting the tape into 5 space strips and arranging themside$by $side we can get a chart representing the motion.

• Each strip will represent 0.1 s of motion.

Typical Shapes of Charts

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Calculations

• Since each strip represents 0.1s of motion, and wecan measure the length of the strips in cm, we canuse speed=distance/time to calculate the speeds.

Scalars and Vectors

• A SCALAR quantity has a size ! Magnitude ", but no direction.

• Examples of scalar Quantities are temperature, time, energy and power.

• A VECTOR quantity has both a magnitude and a direction. Vectorsare often represented with an arrowed line. The direction of the arrowis the direction of the vector and the length of the line represents thesize of the vector.

• Examples of vectors are force, momentum and velocity.

F

BigStone

SandBucket

SmallStone

1

SmallStone

Paper Tray

SandBucket

2

Vacuum

Paper Coin

3

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Gravity

• Experiment 1

• Both Stones Land at the same time.

• Gravity makes them fall at the same rate.• Experiment 2

• Stone landed first.

• Air Resistance slowed down the paper tray.

• Experiment 3

• Both coin & paper land at the same time.

Weight and Mass

• Weight is a force. It tells us how heavy somethingis. It is measured in newtons ! N ". It changesdepending upon the size of gravity. ! Trip to themoon "

• Mass tells us how much substance there is in anobject. It is measured in kilograms ! kg ". It never

changes.

• On Earth we multiply mass by 10 to get weight.

Density

• Density tells us how compact the mass is in a material.

• It is given by:

or

•Stick to one set of units.

•Water has a density of 1000 kg/ ! 3 or 1 g/c ! 3.

•Materials with a smaller density than water will float,materials with a higher density than water will sink.

Density ( kg m3) =

mass(kg)

volume(m3)

Density ( g cm3) =

mass(g)

volume(cm3)

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Density CalculationComplete the following table:

ObjectDensity ! kg/

m3 "Mass ! kg " Volume ! m3 "

A 4000 2

B 8000 4

C 2000 1000

D 2000 4

a " Which object has the greatest mass?

b " Which has the smallest volume?

c " Which objects could be made of the same substance?

d " Which object would float on water?

Irregular objects• The volume of a liquid can be determined using a

measuring cylinder.

• The volume of irregular objects has to be found bydisplacement.

Hooke’s Law

• Hooke’s Law states that the extension in a spring isproportional to the load applied.

The constant of proportionality is called the SpringConstant.

load ! extension

or

F = kx

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Extension/Force Graphs

• A graph can be plotted to show how Force varies with extension for a spring.

• The graph shows proportionality up to a pointcalled the ‘proportionality limit’.

• With increased extension, the spring will reach apoint at which it will not return to its original shape. This is called the elastic limit. The spring shows‘plastic’ behaviour beyond here.

Load/Extension Graphs

• A graph can be plotted to show how extension varies with load for a spring.

• The graph shows proportionality up to a pointcalled the ‘proportionality limit’.

• With increased load, the spring will reach a point at which it will not return to its original shape. This iscalled the elastic limit. The spring shows ‘plastic’behaviour beyond here.

Extension/Force Graphs

extension

Load0

ProportionalityLimit

Linear Region

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Newton’s 1st Law

• If the forces around an object balance ! resultant0N ", then it will either:

• Remain at rest

or

• Move at a constant speed in a straight line.

• ! This is the same as saying constant velocity ".

Exam les of 1st Law

Remains at rest Moves at aconstant speed

in a straightline

Normal

Air Air

Gravity

Normal

Gravity

Oil Tube Experiment

Gravity

FluidResistance

Falls at aconstant

speed in astraight line.

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Unbalanced Forces

• If the forces around an object do not balance, thenthey will cause the object to accelerate ! ordecelerate ".

• The rate of the acceleration depends upon themass of the object.

• The quantities are linked by the followingequation:

F ( N ) = m(kg)! a(m s2)

Questions

• 1. What will be the Force needed to produce anacceleration of 2m/s2 on a mass of 4 kg ?

• 2. What will be the Force needed to produce anacceleration of 5m/s2 on a mass of 42 kg ?

• 3. What will be the acceleration produced when aForce of 50N acts upon a mass of 10 kg ?

Newton’s Laws Calculation

A front wheel drive car is travelling at constant velocity. Q is the force of the air on the moving car.P is the total upward force on both front wheels.

! a " Explain why P= 4 000N, Q= 400N

! b " Calculate the mass of the car.

! c " The 400 N driving force to the left is suddenly doubled.

! i " Calculate the resultant forward driving force.

! ii " Calculate the acceleration of the car.

! iii " Sketch a graph showing how the velocity of the car changes with time ! start the graph justbefore the driving force is doubled. "

400 N

P 6000 N

Q

10 000 N

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Circular Motion• When an object is moving in a circle, it must be experiencing a

force TOWARDS THE CENTRE of the circle.

• We call this the CENTRIPETAL Force.

• This should not be confused with CENTRIFUGAL Force.

• The centripetal force is directed at right angles to the object’s velocity.

object’s path

direction of force

Questions

• For each of the following examples, draw a sketch toshow the situation, name the force providing thecircular motion, and indicate its direction:

• A " The Earth orbiting the Sun.

• B " A car rounding a bend.

• C " A hammer$thrower winding into his throw.

Moments

• A moment is a turning force.

• It is given by:

Moment( Nm) = Force( N )! distance(m)

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Example

• Calculate the moment produced:

0.1m

100N

The Principle of Moments• If a lever is balanced ! in equilibrium " then the total

clockwise moments equal the total anti$clockwisemoments. It will not move.

• Because of Newton’s 1st Law, the forces must alsobalance.

Anti$clockwisemoments

Clockwisemoments

Results

Left-Hand Side Right-Hand Side

Weight Distance W x d Weight Distance W x d

2 8 4 ?

3 4 ? 6

5 2 2 ?

6 3 ? 2

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Moments Questions

• 1. Explain why a mechanic would choose a long $armspanner to undo a tight nut.

• 2. In the following diagram, what is the weight of X ?

X 4N

20 cm 25 cm

Uses of Levers

• Spanner

• Nutcracker

• Scissors

Centre of Mass

• Centre of mass is the point on an object that is the‘average’ position of the mass of the object.

• The centre of gravity is a point on all objects through which forces appear to act.

• The two points are the same.

• The centres of mass of regular objects are obvious. Theyalways lie on a line of symmetry.

• They are the point under which we place a pivot to balancethe object.

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Regular Objects

Stability

• Stability tells us how secure something is on the ground.

• If something is stable, then it will not topple easily.

• There are two factors to consider when changing thestability of an object:

• The area of the object’s base.• The position of the centre of mass of the object.

• A stable object will have a BIG base, and a LOW centre of gravity.

Simple Addition

• If two vectors are parallel, then they can be simplyadded or subtracted to give a resultant.

3N 5N

2N

RESULTANT

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2D$ Addition

• If the vectors are not parallel we have to draw a scalediagram and add the vectors to give a resultant.

3m/s 2m/s

RESULTANT

3m/s

2m/s

Examples

• 1. A plane flies North at 40 m/s. The windblows to the East at 15 m/s. Calculate theoverall velocity.

• 2i ". A falling ball has a weight of 10 N and

and air resistance of 2 N . What the e# ectivedownward force on it?

• ii " A wind blows to the left with a force of2N. Using a vector diagram, calculate theresultant force on the ball.

EnergyForms

ElasticPotentialEnergy

Heat

Kinetic

Electricity

Sound

GravitationalPotentialEnergy

Chemical

PotentialEnergy

Light

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Energy Transfers

• When any physical process takes place, there is a transferof energy from one form to another.

• This can be shown in an energy flow diagram:

T.VElectricity

Light

Sound

Heat

Examples of Energy Transfers

• A burning match

• A lightbulb

• A petrol lawnmower

• A car

• Headphones

• A microphone

• A waterfall

Kinetic Energy

• All objects that are moving have kinetic energy.

• It depends on the mass of the object and its speed.

• It is measured in joules.

KE =1

2

mv2

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Gravitational Energy

• Gravitational energy is stored in objects thatare at a height.

•It depends upon the mass of the object, andhow high the object is.

• It measured in joules.

GPE = mgh

The Principle of theConservation of Energy

• Energy cannot be created or destroyed, it simplymoves from one form to another.

• When energy moves from one form to another, thetotal AMOUNT of energy remains the same.

• A certain amount of heat energy is always lost to thesurroundings in any process.

E&ciency • E&ciency tells us how e# ective a process or energy transfer is.

• The more useful energy that is produced, for the least input energy, themore e&cient the process is.

• E&ciency has no unit, and can be expressed as a decimal or percentage.

• It can be the ratio of power output to input, or energy output to inputfor a process

Efficiency =output

input (!100)

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Work Done

• Work is a type of energy change and is measuredin Joules.

•For work to be done, a force must be acting uponan object as it moves through a distance.

• The Work Done is given by:

Work Done ( J )=Force( N )! Distance(m)

Power• Power is the rate at which energy is transferred.

• It is also the rate at which Work is done.

• The unit for Power is Watts ! W ".

• Power is calculated from either:

or

Power(W )= Energy Change( J )Time Taken(s)

Power(W )=Work Done( J )

Time Taken(s)

Calculating Personal Power

• Measure your weight in newtons.

•Measure the height of the steps in metres.

• Measure the time taken to climb the steps in seconds.

• Calculate the Work Done in joules.

• Calculate the Power of your legs in Watts.

heighttime

weight

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Pressure

• Pressure tells us how concentrated a force is.

• It is calculated from:

or

Stick to one set of units

Pressure( N m2)= Force( N )

Area(m2)

Pressure( N cm2)=

Force( N )

Area(cm2)

Examples

1. Calculate the Volume of the block.

2. Calculate the block’s density.

3. Calculate the block’s weight.

4. Calculate the area in contact with the ground.

1c !

1c !

2c !

20 g

Examples

• Why do camels have large flat feet?

• Why is it easier to walk in snow shoes in the snow?

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Pressure in Liquids

Pressure in a liquid is due tothe weight of the liquidabove a point.

Pressure increases withdepth.

Pressure will also increase with density of liquid! more weight ".

We can calculate pressurefrom:

P = ! gd

Direction

• The pressure in a liquid actsin ALL directions equally at apoint.

• This is why bubbles arespherical.

Questions

• 1a ". Draw a diagram of the cross section of a dam.

• b " Explain why it has this shape.

• 2. Calculate the pressure on a scuba diver at a depthof 20 !. ! The density of water is 1000 kg/ ! 3 "

• 3. Describe a demonstration to show that Pressureincreases with depth in a liquid.

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Non$Renewable EnergyResources

• Non$Renewable resources are resources that areused up and cannot be easily replaced. Examples arefossil fuels and Nuclear fuels.

Renewable Energy Resources

• Renewable Energy Resources are energy resourcesthat keep running and do not run$out easily .

The EnergyCrisis

• Transport

• Electricity

• Fossil Fuels

• Pollution

• Depletion

Energy usage

• Energy

Density

• Pollution

• Safety

Nuclear Fission

Renewable

Alternatives

• Advantages

• Unrel iable

• Not Controllable

• Energy Density

Nuclear Fusion

• Safety • Pollution

• Problems

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General PhysicsQuantity and

symbolDefinition/Word equation

Symbol

equationUnits

Scalar Quantities Scalar quantities only have a magnitude.

Vector Quantities Vector quantities have a magnitude, a directionand a point of application.

Average Speed, s

Speed is the rate of change of distance. It is ascalar quantity.

Speed = Total distance

Total time

For constant acceleration situations, the

average speed is also equal to the average of

the initial and final speeds.

s = initial speed + final speed

2

s = dt

s = u + v

2

m/s

cm/s

km/h

Velocity

Velocity is the rate of change of displacement.

It is speed in a given direction. A vector

quantity.

m/s

cm/s

km/h

Acceleration, a

Acceleration is the rate of change of velocity.

Acceleration = Final velocity – initial velocity

Time

a = v – u

tm/s

2

Mass, mMass is a property of a body that resists change

in motion.

Weight, W, F

Weight is the force on a mass due to the

gravitational field of the Planet. It changes

from planet to planet. Weights can becompared using a balance.

Weight = mass x acceleration due to gravityWeight = mass x gravitational field strength

W = m x g Newtons, N

Density, !

Density is the mass per unit volume.Density = mass

volume

! = m

V

Kg/m3

g/cm3

Force, F

A force is a push or a pull; it can change the

shape, direction, and/or speed of an object.Force = mass x acceleration

F = m a Newtons,

N

Load, (Hookes

law)

Load = spring constant x extension

Load " extension

F = k l

F " l

Newtons,

N

Moment

A moment is the turning affect of a force.

Moment = force x perpendicular distance from

the pivot

Moment = F d Nm

Equilibrium

When there is no resultant force AND no

resulting turning affect, a system is in

equilibrium.

Work done, W, EWork done = Force x distance in the direction

of the force = change in energyW = F d = #E Joules, J

Kinetic energy,

KE

Kinetic energy is the energy of a body due to

its motion.

Kinetic energy = $ x mass x velocity2KE = $ m v

2 Joules, J

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Gravitational

energy, GPE

Gravitational potential energy is the energy of

a body due to its position in the gravitational

field.

Gravitational energy =mass x acceleration due

to gravity x height gained/lost

GPE = m g h Joules, J

Efficiency Efficiency = useful output x 100%total input

%

Power, P

Power is the rate at which energy is converted.

Power = work done

time takenPower = energy change

time taken

P = E

tWatts, W

Pressure, p, PPressure = force

area

P = F

A

N/m2

Pascals,Pa

millibar

Fluid Pressure, p,

P

Pressure = density of fluid x acceleration due

to gravity x height of fluid aboveP = ! g h

N/m2

Pascals,Pa

Millibar

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iGCSE Physics

Past Paper Questions

Paper 1 Compilation

General Physics

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2

0625/1/M/J/02

1 The diagram shows the level of liquid in a measuring cylinder.

What is the volume of the liquid?

A 24 cm3 B 28 cm3 C 29 cm3 D 32 cm3

2 A cylindrical can is rolled along the ruler shown in the diagram.

The can rolls over twice.

What is the circumference (distance all round) of the can?

A 13 cm B 14 cm C 26 cm D 28 cm

0 cm 5 10 15 20 25 30 cm

mark oncan

can rolled

starting position final position

30

20

cm3

liquid

1.

2.

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3

0625/1/M/J/02 [Turn over

3 The graph shows how the speed of a car changes with time.

Which of the following gives the distance travelled in time interval OR?

A the area OPQR

B the length PQ

C the length (QR – PO)

D the ratio QR/PO

4 A snail crosses a garden path 30 cm wide at a speed of 0.2 cm/s.

How long does the snail take?

A 0.0067s B 6.0 s C 15 s D 150s

5 What are correct units used for mass and for weight?

30 cmmovementof snail

snail

speed

P

Q

RO time

mass weight

A kg kg

B kg N

C N kg

D N N

3.

4.

5.

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4

0625/1/M/J/02

6 Two objects X and Y are placed on a beam as shown. The beam balances on a pivot at itscentre.

What does this show about X and Y?

A They have the same mass and the same density.

B They have the same mass and the same weight.

C They have the same volume and the same density.

D They have the same volume and the same weight.

7 A shop-keeper places two identical blocks of cheese on a set of scales and notices that theircombined mass is 240 g. Each block measures 2.0cm x 5.0 cm x 10.0 cm.

What is the density of the cheese?

A 0.42g/cm3 B 0.83g/cm3 C 1.2g/cm3 D 2.4g/cm3

8 The table shows the length of a wire as the load on it is increased.

Which subtraction should be made to find the extension caused by the 20 N load?

A 54.1 cm – 0cm

B 54.1 cm – 50.0cm

C 54.1 cm – 52.1cm

D 56.3 cm – 54.1cm

g

X

Y

pivot

load / N 0 10 20 30

length / cm 50.0 52.1 54.1 56.3

6.

7.

8.

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5


9 A child tries to push over a large empty oil drum.

Where should the drum be pushed to topple it over with least force?

10 Which device is designed to convert chemical energy into kinetic energy (energy of motion)?

A an a.c. generator

B a battery-powered torch

C a car engine

D a wind-up mechanical clock

11 A ball is released from rest and rolls down a track from the position shown.

What is the furthest position the ball could reach?

ball

startshere

A

B

C

D

A B C D

9.

10.

11.

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6

0625/1/M/J/02

12 Two sharp nails and two blunt nails are held on a piece of wood. Each nail is hit with the samehammer with the same amount of force.

When it is hit, which nail causes the greatest pressure on the wood?

13 The diagram shows a manometer connected to a container of carbon dioxide.

Which statement correctly describes the pressure exerted by the carbon dioxide?

A It is equal to the atmospheric pressure.

B It is equal to 5cm of mercury.

C It is equal to 5 cm of mercury above atmospheric pressure.

D It is equal to 5 cm of mercury below atmospheric pressure.

carbon dioxide

container

mercury

manometer

5

cm

A B

hammer

sharp nails

C Dhammer

blunt nails

12.

13.

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2

0625/01/M/J/03

1 A glass tank contains some water.

The length QR and the width RS of the tank are known.

What other distance needs to be measured in order to be able to calculate the volume of the

water?

A ST B SV C TU D TV

2 A stopwatch is used to time a race. The diagrams show the watch at the start and at the end of therace.

How long did the race take?

A 45.7s B 46.0s C 46.5s D 47.0s

45

30

15

seconds

start

50

55 60 5

10

20

2535

40

45

30

15

seconds

end

50

55 60 5

10

20

2535

40

water

Q

R

S

T

V

U

14.

15.

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3 The diagram shows a speed-time graph for a body moving with constant acceleration.

What is represented by the shaded area under the graph?

A acceleration

B distance

C speed

D time

4 A tunnel has a length of 50km. A car takes 20min to travel between the two ends of the tunnel.

What is the average speed of the car?

A 2.5km/h

B 16.6km/h

C 150km/h

D 1000km/h

5 Which statement is correct?

A Mass is a force, measured in kilograms.

B Mass is a force, measured in newtons.

C Weight is a force, measured in kilograms.

D Weight is a force, measured in newtons.

speed

time0

0

16.

17.

18.

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4

0625/01/M/J/03

6 Three children, X, Y and Z, are using a see-saw to compare their weights.

Which line in the table shows the correct order of the children’s weights?

7 What apparatus is needed to determine the density of a regularly-shaped block?

A a balance and a ruler

B a balance and a forcemeter (spring balance)

C a measuring cylinder and a ruler

D a measuring cylinder and a beaker

8 A spring is suspended from a stand. Loads are added and the extensions are measured.

Which graph shows the result of plotting extension against load?

00

e x t e n s i o n

load

A

00

e x t e n s i o n

load

B

00

e x t e n s i o n

load

C

00

e x t e n s i o n

load

D

spring

stand

loadsrule

X Y Y Z X Z

heaviest ←→ lightest

A X Y Z

B X Z Y

C Y X Z

D Y Z X

19.

20.

21.

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9 A student uses a stand and clamp to hold a flask of liquid.

Which diagram shows the most stable arrangement?

10 What is the source of the energy converted by a hydro-electric power station?

A hot rocks

B falling water

C oil

D waves

11 A labourer on a building site lifts heavy concrete blocks onto a lorry. Lighter blocks are now lifted

the same distance in the same time.

What happens to the work done in lifting each block and the power exerted by the labourer?

A B C D

work done in power exerted bylifting each block labourer

A decreases decreases

B decreases remains the same

C increases increases

D remains the same increases

22.

23.

24.

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6

0625/01/M/J/03

12 The diagram shows an instrument used to measure gas pressure.

What is the instrument called?

A ammeter

B barometer

C manometer

D thermometer

13 The diagrams show two divers swimming in the sea and two divers swimming in fresh water. Seawater is more dense than fresh water.

On which diver is there the greatest pressure?

14 When water evaporates, some molecules escape.

Which molecules escape?

A the molecules at the bottom of the liquid with less energy than others

B the molecules at the bottom of the liquid with more energy than others

C the molecules at the surface with less energy than others

D the molecules at the surface with more energy than others

fresh waterC

D

2

m

0

m

4

m

6

m

sea waterA

B

2

m

0

m

4

m

6

m

liquid

25.

26.

27.

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1 The diagram shows a measuring cylinder.

10

20

30

40

50

60

70

80

90

100

Which unit wou ld be most suitable for its sca le?

A mm2 B mm3 C cm2 D cm 3

2 A piece of cotton is measured between two points on a ruler .

1cm 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

cotton

When the leng th of cotton is wound clos e ly around a pen , it goe s round six times.

pen six turns of cotton

Wha t is the distance once round the pen?

A 2.2 cm B 2.6 cm C 13 .2 cm D 15 .6 cm

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3 The diagram shows the speed-time graph for an object moving at constant speed.

2

00 3 4

time/s

speed

m / s

1

1 2

What is the distance travelled by the object in the first 3 s?

A 1.5m B 2.0m C 3.0m D 6.0m

4 A small steel ball is dropped from a low balcony.

Ignoring air resistance, which statement describes its motion?

A It falls with constant acceleration.

B It falls with constant speed.

C It falls with decreasing acceleration.

D It falls with decreasing speed.

5 Which statement about the mass of a falling object is correct?

A It decreases as the object falls.

B It is equal to the weight of the object.

C It is measured in newtons.

D It stays the same as the object falls.

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6 The weights of four objects, 1 to 4, are compared using a balance.

1

2

3

2 4

2

Which object is the lightest?

A object 1 B object 2 C object 3 D object 4

7 Which of the following is a unit of density?

A cm3 / g

B g/cm2

C g/cm3

D kg/m2

8 A piece of card has its centre of mass at M.

Which diagram shows how it hangs when suspended by a thread?

A B C D

M M

M

M

9 An experiment is carried out to measure the extension of a rubber band for different loads.

The results are shown below.

load /N 0 1 2 3

length / cm 15.2 16.2 18.6

extension / cm 0 1.0 2.1 3.4

Which figure is missing from the table?

A 16.5 B 17.3 C 17.4 D 18.3

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10 The diagram shows a man d iving into water .

Which form of energy is increasing as he fa lls?

A chemica l

B gravitation a l

C kine tic

D stra in

11 A boy and a girl run up a hill in the same time .

boy weighs 600 N girl weighs 500 N

The boy we ighs more than the girl.

Which statement is true about the power produced?

A The boy produces more power.

B The girl produces more power.

C They both produce the same power.

D It is impossible to te ll who produces more power.

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12 The diagram shows a s imp le mercury barometer . The barome ter rea ding is h cm of mercury.

mercury

S

h

What is the pressure a t S?

A approximate ly zero

B atmospheric pressure

C atmospheric pressure + h cm of mercury

D h cm of mercury

13 Two boys X and Y e ach have the same tota l we igh t and are stand ing on soft ground.

X Y

Which boy is more like ly to sink into the soft ground and why?

boy more

like ly to sink

pressure on soft ground

A X larger than Y

B X sma ller than Y

C Y larger than X

D Y sma ller than X

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1 A decorator wishes to calculate the area of a bathroom tile so that he can estimate the amount ofadhesive that he needs to buy.

What must he use?

A a measuring cylinder only

B a ruler only

C a measuring cylinder and a clock only

D a measuring cylinder and a ruler only

2 The three balls shown are dropped from a bench.

aluminium lead wood

Which balls have the same acceleration?

A aluminium and lead only

B aluminium and wood only

C lead and wood only

D aluminium, lead and wood

3 A car accelerates from traffic lights. The graph shows how the car’s speed changes with time.

time / s

20

100 0

speed

m / s

How far does the car travel before it reaches a steady speed?

A 10 m B 20 m C 100 m D 200 m

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[Turn over

4 Which statement is correct?

A The mass of a bottle of water at the North Pole is different from its mass at the Equator.

B The mass of a bottle of water is measured in newtons.

C The weight of a bottle of water and its mass are the same thing.

D The weight of a bottle of water is one of the forces acting on it.

5 Two blocks X and Y are placed on a beam as shown. The beam balances on a pivot at its centre.

XY

pivot

What does this show about X and Y?

A They have the same mass and the same density.

B They have the same mass and the same weight.

C They have the same volume and the same density.

D They have the same volume and the same weight.

6 The masses of a measuring cylinder before and after pouring some liquid into it are shown in thediagram.

200

100

cm3

mass = 80 g

200

100

cm3

mass = 180 g

liquid

What is the density of the liquid?

A120

100g / cm3 B

140

100g / cm3 C

120

180g / cm3 D

140

180g / cm3

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7 A girl and a boy are pulling in opposite directions on a rope. The forces acting on the rope areshown in the diagram.

200 N

rope

150 N

girl boy

Which single force has the same effect as the two forces shown?

A 50 N acting towards the girl

B 350 N acting towards the girl

C 50 N acting towards the boy

D 350 N acting towards the boy

8 Objects with different masses are hung on a 10 cm spring. The diagram shows how much thespring stretches.

100 g

M

10 cm

20 cm

30 cm

The extension of the spring is directly proportional to the mass hung on it.

What is the mass of object M?

A 110 g B 150 g C 200 g D 300 g

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9 What is designed to change electrical energy into kinetic energy?

A capacitor

B generator

C motor

D transformer

10 A power station uses nuclear fission to obtain energy.

In this process, nuclear energy is first changed into

A chemical energy.

B electrical energy.

C gravitational energy.

D internal energy.

11 A ball is released from rest and rolls down a track from the position shown.

What is the furthest position the ball could reach?

A

B

C

D

ball

starts

here

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12 A water manometer is used to measure the pressure of a gas supply to a house. It gives areading of h cm of water.

gassupply

h cm

Why is it better to use water rather than mercury in this manometer?

A h would be too large if mercury were used.

B h would be too small if mercury were used.

C The tube would need to be narrower if mercury were used.

D The tube would need to be wider if mercury were used.

13 A farmer has two carts. The carts have the same weight, but one has four narrow wheels and theother has four wide wheels.

narrow wheel wide wheel

In rainy weather, which cart sinks l ess into soft ground, and why?

cart wheels why

A narrow greater pressure on the ground

B narrow less pressure on the ground

C wide greater pressure on the ground

D wide less pressure on the ground

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© UCLES 2006 0625/01/M/J/06

1 A measuring cylinder contains some water. When a stone is put in the water, the level rises.

150

100

50

cm3

150

100

50

cm3

200 200

stone

What is the volume of the stone?

A 50 cm3 B 70 cm3 C 75 cm3 D 125 cm3

2 The graph represents the movement of a body accelerating from rest.

1 2 3 4 5

10

8

6

4

2

0

time / s

speed

m / s

After 5 seconds how far has the body moved?

A 2 m B 10 m C 25 m D 50 m

3 A child is standing on the platform of a station, watching the trains.

A train travelling at 30 m / s takes 3 s to pass the child.

What is the length of the train?

A 10 m B 30 m C 90 m D 135 m

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4 Below are four statements about the effects of forces on objects.

Three of the statements are correct.

Which statement is incorrect?

A A force can change the length of an object.B A force can change the mass of an object.

C A force can change the shape of an object.

D A force can change the speed of an object.

5 A simple balance has two pans suspended from the ends of arms of equal length. When it isbalanced, the pointer is at 0.

0

pointer

pan X pan Y

armpivot

Four masses (in total) are placed on the pans, with one or more on pan X and the rest on pan Y.

Which combination of masses can be used to balance the pans?

A 1 g, 1 g, 5 g, 10 g

B 1 g, 2 g, 2 g, 5 g

C 2 g, 5 g, 5 g, 10 g

D 2 g, 5 g, 10 g, 10 g

6 A person measures the length, width, height and mass of a rectangular metal block.

Which of these measurements are needed in order to calculate the density of the metal?

A mass only

B height and mass only

C length, width and height only

D length, width, height and mass

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7 Two forces act on an object.

In which situation is it impossible for the object to be in equilibrium?

A The two forces act in the same direction.

B The two forces act through the same point.

C The two forces are of the same type.

D The two forces are the same size.

8 The diagram shows four models of buses placed on different ramps.

centre

of mass

centre

of mass

centre

of mass

centre

of mass

How many of these models will fall over?

A 1 B 2 C 3 D 4

9 Which form of energy do we receive directly from the Sun?

A chemical

B light

C nuclear

D sound

10 A labourer on a building site lifts a heavy concrete block onto a lorry. He then lifts a light block thesame distance in the same time.

Which of the following is true?

work done in lifting theblocks

power exerted by labourer

A less for the light block less for the light block

B less for the light block the same for both blocks

C more for the light block more for the light block

D the same for both blocks more for the light block

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0625 / 01 / M / J / 06 [Turn over

11 The diagram shows a thick shee t o f g lass .

Which edge must it s tand on to cause the greatest pressure?

A

D

C

B

12 A manometer is be ing used to measure the pressure of the gas ins ide a tank . A, B, C and D show the manometer at d ifferent times.

A t which time is the ga s pressure ins ide the tank grea test?

gas

A B C D

13 Brownian motion is seen by looking at smoke particles through a m icroscope .

How do the smoke particles move in Brownian motion?

A a ll in the same dire ction

B a t randomC in circ les

D vibrating about fixed points

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iGCSE Physics


Paper 3 Compilation

General Physics

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1 A group of students attempts to find out how much power each student can generate. Thestudents work in pairs in order to find the time taken for each student to run up a flight ofstairs.The stairs used are shown in Fig. 1.1.

Fig. 1.1

(a) Make a list of all the readings that would be needed. Where possible, indicate how theaccuracy of the readings could be improved.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [4]

(b) Using words, not symbols, write down all equations that would be needed to work outthe power of a student.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(c) (i) When the student has reached the finishing point and is standing at the top of thestairs, what form of energy has increased to its maximum?

...................................................................................................................................

(ii) Suggest why the total power of the student is greater than the power calculated bythis method.

...................................................................................................................................

...................................................................................................................................[3]

starting point

finishing point

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3


2 A small rubber ball falls vertically, hits the ground and rebounds vertically upwards.Fig. 2.1 is the speed-time graph for the ball.

Fig. 2.1

(a) Using information from the graph, describe the following parts of the motion of the ball.

(i) part AB

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) part DE

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[3]

(b) Explain what is happening to the ball along the part of the graph from B through C to D.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(c) Whilst the ball is in contact with the ground, what is the

(i) overall change in speed,

change in speed = ........................................

(ii) overall change in velocity?

change in velocity = ......................................[2]

10

8

6

4

2

00

0.5 1.0 1.5 2.0time/s

speed

m/ s

B

D

C EA

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4

0625/3/M/J/02

(d) Use your answer to (c) to explain the difference between speed and velocity.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(e) Use the graph to calculate the distance travelled by the ball between D and E.

distance travelled = ..................................[2]

(f) Use the graph to calculate the deceleration of the ball between D and E.

deceleration = ..................................[2]

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2

0625/3/M/J/03

1 Fig. 1.1 shows apparatus that may be used to compare the strengths of two springs of thesame size, but made from different materials.

Fig. 1.1

(a) (i) Explain how the masses produce a force to stretch the spring.

...................................................................................................................................

(ii) Explain why this force, like all forces, is a vector quantity.

...................................................................................................................................

...................................................................................................................................[2]

(b) Fig. 1.2 shows the graphs obtained when the two springs are stretched.

Fig. 1.2

00

5

10

15

20force/N

10 20 30 40

extension/mm

spring 1pring

spring 2pring

spring 1

spring 2

spring

masses

scale

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(i) State which spring is more difficult to extend. Quote values from the graphs tosupport your answer.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) On the graph of spring 2, mark a point P at the limit of proportionality. Explain yourchoice of point P.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(iii) Use the graphs to find the difference in the extensions of the two springs when aforce of 15N is applied to each one.

difference in extensions = ..................................[6]

2 The speed of a cyclist reduces uniformly from 2.5 m/s to 1.0m/s in 12 s.

(a) Calculate the deceleration of the cyclist.

deceleration = ..................................[3]

(b) Calculate the distance travelled by the cyclist in this time.

distance = ..................................[2]

For

Examiner’s

Use

4.

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3 Fig. 3.1 shows the arm of a crane when it is lifting a heavy box.

Fig. 3.1

(a) By the use of a scale diagram (not calculation) of the forces acting at P, find the weightof the box. [5]

40° 30°

950N

1220N

P

box

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(b) Another box of weight 1500 N is raised vertically by 3.0m.

(i) Calculate the work done on the box.

work done = ..................................

(ii) The crane takes 2.5 s to raise this box 3.0 m. Calculate the power output of thecrane.

power = ..................................

[4]

4 Fig. 4.1 shows a sealed glass syringe that contains air and many very tiny suspended dustparticles.

Fig. 4.1

(a) Explain why the dust particles are suspended in the air and do not settle to the bottom.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

(b) The air in the syringe is at a pressure of 2.0 ×105 Pa. The piston is slowly moved into thesyringe, keeping the temperature constant, until the volume of the air is reduced from80cm3 to 25 cm3. Calculate the final pressure of the air.

pressure = ..................................[3]

syringe

seal

dust particles

piston

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0625/03 M/J/04

1 Fig. 1.1 shows a cycle track.

Fig. 1.1

A cyclist starts at A and follows the path ABCDEB.

The speed-time graph is shown in Fig. 1.2.

Fig. 1.2

(a) Use information from Fig. 1.1 and Fig.1.2 to describe the motion of the cyclist

(i) along AB,

...................................................................................................................................

(ii) along BCDEB.

...................................................................................................................................

...................................................................................................................................[4]

0

1

0

2

3

4

5

6

30 40 5010 20 60 70 80 90 100

time

/

s

speed

m

/

s

A

B C D E B

A B

E C

D

v = 6 m/s

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0625/03 M/J/04 [Turn over

(b) The velocity v of the cyclist at C is shown in Fig.1.1.

State one similarity and one difference between the velocity at C and the velocity at E.

similarity ...........................................................................................................................

difference ......................................................................................................................[2]

(c) Calculate

(i) the distance along the cycle track from A to B,

distance = …………………

(ii) the circumference of the circular part of the track.

circumference = …………………[4]

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2 Fig. 2.1 shows a rock that is falling from the top of a cliff into the river below.

Fig. 2.1

(a) The mass of the rock is 75 kg. The acceleration of free fall is 10m/s2.Calculate the weight of the rock.

weight = …………………[1]

(b) The rock falls from rest through a distance of 15 m before it hits the water.Calculate its kinetic energy just before hitting the water. Show your working.

kinetic energy = …………………[3]

(c) The rock hits the water. Suggest what happens to the kinetic energy of the rock duringthe impact.

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

cliff

fallingrock

river

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0625/03 M/J/04 [Turn over

3 A large spring is repeatedly stretched by an athlete to increase the strength of his arms.Fig. 3.1 is a table showing the force required to stretch the spring.

Fig. 3.1

(a) (i) State Hooke’s law.

...................................................................................................................................

...............................................................................................................................[1]

(ii) Use the results in Fig. 3.1 to show that the spring obeys Hooke’s law.

[1]

(b) Another athlete using a different spring exerts an average force of 400 N to enable herto extend the spring by 0.210 m.

(i) Calculate the work done by this athlete in extending the spring once.

work done = …………………

(ii) She is able to extend the spring by this amount and to release it 24 times in 60 s.Calculate the power used by this athlete while doing this exercise.

power = …………………[4]

For

Examiner’s

Use

© UCLES 2004

extension of spring/m 0.096 0.192 0.288 0.384

force exerted to produce extension/N 250 500 750 1000

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0625/03/M/J/05

1 A solid plastic sphere falls towards the Earth.

Fig. 1.1 is the speed-time graph of the fall up to the point where the sphere hits the Earth’ssurface.

Fig. 1.1

(a) Describe in detail the motion of the sphere shown by the graph.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [3]

0

20

P

Q

R S T

40

60

80

100

120

140

speedm / s

100 20 30 40 50 60 70 80 90 100 110

time / s

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(b) On Fig. 1.2, draw arrows to show the directions of the forces acting on the sphere whenit is at the position shown by point S on the graph. Label your arrows with the names ofthe forces. [2]

Fig. 1.2

(c) Explain why the sphere is moving with constant speed at S.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(d) Use the graph to calculate the approximate distance that the sphere falls

(i) between R and T,

distance = ………………. [2](ii) between P and Q.

distance = ………………. [2]

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Examiner’s

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2 Fig. 2.1 shows a simple pendulum that swings backwards and forwards between P and Q.

Fig. 2.1

(a) The time taken for the pendulum to swing from P to Q is approximately 0.5 s.

Describe how you would determine this time as accurately as possible.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(b) (i) State the two vertical forces acting on the pendulum bob when it is at position R.

1. ...............................................................................................................................

2. .......................................................................................................................... [1]

(ii) The pendulum bob moves along the arc of a circle. State the direction of theresultant of the two forces in (i).

.............................................................................................................................. [1]

(c) The mass of the bob is 0.2 kg. During the swing it moves so that P is 0.05 m higher

than R.

Calculate the increase in potential energy of the pendulum bob between R and P.

potential energy = ………………. [2]

support

string

pendulum bobP

R Q

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Examiner’s

Use

© UCLES 2005

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3 A mass of 3.0kg accelerates at 2.0m/s2 in a straight line.

(a) State why the velocity and the acceleration are both described as vector quantities.

..........................................................................................................................................

..................................................................................................................................... [1]

(b) Calculate the force required to accelerate the mass.

force = ………………. [2]

(c) The mass hits a wall.

The average force exerted on the wall during the impact is 120 N.The area of the mass in contact with the wall at impact is 0.050 m2.Calculate the average pressure that the mass exerts on the wall during the impact.

pressure = ………………. [2]

For

Examiner’s

Use

© UCLES 2005

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0625/03/M/J/06

For

Examiner’s

Use

© UCLES 2006

1 A bus travels from one bus stop to the next. The journey has three distinct parts. Stated inorder they are

uniform acceleration from rest for 8.0 s, uniform speed for 12 s, non-uniform deceleration for 5.0 s. Fig. 1.1 shows only the deceleration of the bus.

5

0

10

15

50 10 15 20 25

speed

m/s

time/s

Fig. 1.1

(a) On Fig. 1.1, complete the graph to show the first two parts of the journey. [3]

(b) Calculate the acceleration of the bus 4.0 s after leaving the first bus stop.

acceleration = ........................ [2]

(c) Use the graph to estimate the distance the bus travels between 20 s and 25 s.

estimated distance = ........................ [2]

(d) On leaving the second bus stop, the uniform acceleration of the bus is 1.2 m / s2. Themass of the bus and passengers is 4000 kg.

Calculate the accelerating force that acts on the bus.

force = ........................ [2]

(e) The acceleration of the bus from the second bus stop is less than that from the first busstop.

Suggest two reasons for this.

1. ......................................................................................................................................

..........................................................................................................................................

2. ......................................................................................................................................

......................................................................................................................................[2]

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For

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© UCLES 2006

2 A student sets up the apparatus shown in Fig. 2.1 in order to find the resultant of the twotensions T1 and T2 acting at P. When the tensions T1, T2 and T3 are balanced, the anglesbetween T1 and the vertical and T2 and the vertical are as marked on Fig. 2.1.

vertical

board

pulley

pulley

69°44°

P

T1 = 6.0 N T2 = 8.0 N

T3

Fig. 2.1

In the space below, draw a scale diagram of the forces T1 and T2. Use the diagram to find theresultant of the two forces.

State

(a) the scale used, scale = ........................................

(b) the value of the resultant, value = ........................................

(c) the direction of the resultant. direction = ........................................

[6]

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Use

© UCLES 2006

3 An electric pump is used to raise water from a well, as shown in Fig. 3.1.

pump

ground

well

Fig. 3.1

(a) The pump does work in raising the water. State an equation that could be used tocalculate the work done in raising the water.

......................................................................................................................................[2]

(b) The water is raised through a vertical distance of 8.0 m. The weight of water raised in5.0 s is 100 N.

(i) Calculate the work done in raising the water in this time.

work done = ....................... [1]

(ii) Calculate the power the pump uses to raise the water.

power = ........................ [1]

(iii) The energy transferred by the pump to the water is greater than your answer to (i).Suggest what the additional energy is used for.

..............................................................................................................................[1]

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Topic 2: Thermal Physics

Solids

• The particles in solids are tightly held together by strongforces.

• They vibrate around mean positions.

• The higher the temperature, the more vibrational kineticenergy the particles have.

• Solids have a rigid shape.

Liquids

• In liquids the forces are strong, but the vibrating particles are not fixed in position.

• The particles can move but they are held close to theirneighbours.

• Liquids do not keep their shape.

1

2

3

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Gases• In gases the forces are very weak and they are virtually

free to move around their container.

• The particles occasionally collide.

• Gases expand to fill their container.

• The collisions between the particles and the containerwalls provides pressure.

Changing State

• When a material changes from one state to another, bonds are either broken or created.

• When bonds are broken, heat must be supplied. When bonds are created, heat is released.

• When materials change state there is no change in the

temperature.

Phase Changes

• The phase change from solid to liquid is called ‘fusion’.

• The phase change from liquid to gas is called‘vaporisation’.

• The energy required to effect the phase change is calledthe ‘Latent Heat’.

• The Latent Heat required per kg is called the ‘SpecificLatent Heat’.

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Phases Changes ! Graphical "

Temperature

Time

fusion

vaporisation

liquid

water

Latent Heat Calculations

• The Specific Latent Heat of a material is given the symbol l.

• From the definition, we have the following relationship:

H - J

m - kg

l - J/kg

H = ml

Heat Capacity

• Whilst a material is being heated within a certain stateof matter, its temperature will rise.

• The temperature rise depends upon the mass of thematerial, the type of material and the amount of heatsupplied.

• The property of a material that represents how muchheat is needed to raise its temperature is called its‘Specific Heat Capacity’ and is given the symbol c.

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Calculations• To calculate heat required we use:

H - J

m - kg

C - J/kg/ ºC

!T - ºC

H = mc!T

Constant Volume

• If we increase the temperature of a gas in acontainer at a constant volume, the particles

will move with more energy, and so there willbe more collisions, and so greater pressure:

Pressure increases with Temperature

Constant Pressure

• If we increase the temperature of a gas in a container ata constant pressure, the particles will move with moreenergy, but they need more space to keep the collisionsconstant and so there will be a greater volume:

Volume increases with Temperature

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Constant Temperature• If we keep the temperature of a gas constant, we

keep the kinetic energy of the particles constant.

• Decreasing the volume of the gas’ container willincrease the number of collisions of the particles withthe container.

• The pressure of the gas will increase.

• Pressure and Volume changes are described by thefollowing relationship:

P1V 1 = P

2V 2

Brownian Motion

• When pollen grains are placed on the surface of aliquid and a strong light source is used to illuminatethe pollen, the pollen is seen to move randomly.

• This movement is called ‘Brownian Motion’ andcause by the invisible water particles hitting thepollen grains.

Expansion

• When particles are heated they gain energy.

• They become more spaced#out, and the material gets bigger.

• We say that the material expands.

•Generally, objects expand as they get hotter and contract as they get cooler.

• Liquids expand more than solids on heating, and gases expand more than liquids.

• Solids expand with the greatest force. Gases expand with the least force.

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Questions on Expansion

• Why do walls have expansion joints?

• Why are pylon electrical cables tighter in winter?

• Why do railway lines leave regular gaps betweenthem?

Temperature Scales

• The most common temperature scale that is used is theCelsius scale. This has its zero at the freezing point of water,and the boiling point of water is 100°C.

• In Physics, the Kelvin scale ! or Absolute Temperature scale " isoften used.

• This is often more sensible as the zero is defined as the pointat which the particles have no kinetic energy ! Absolute Zero ".

• To convert between Celsius and Kelvin, we add 273°C.

• A rise of 1K is the same as a rise of 1°C.

Internal Energy

• The Kelvin Temperature is proportional tothe average kinetic energy of the particles.

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Evaporation

• Evaporation is a process by which a liquidcools due to the fact that particles are lostfrom its surface.

• The higher energy particles will be morelikely to leave the liquid, so lowering theaverage KE of the particles remaining in theliquid. The temperature will thus belowered.

• Increasing the exposed surface area of theliquid, or increasing the movement of air willincrease the rate of evaporation.

Changing State

When a material changes from one state to another,bonds are either broken or created. This involves anassociated Internal Energy change.

When bonds are broken, heat must be supplied.

When bonds are created, Heat is released.

Since the energy changes are entirely Internal, thereis no change in kinetic energy of the particles, andhence no change in the temperature of the material.

Thermometry

To make a thermometer, we need a property thatchanges with temperature in a linear fashion.

We then need to calibrate the thermometer bychoosing two fixed points.

The fixed points for calibration are the boiling pointof water ! 100°C " and the freezing point of water! 0°C ".

The scale is then divided into 100 equal parts forinterpolation.

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Liquid in Glass Thermometers

• Liquid in glass thermometers have liquid ina glass bulb. As the liquid is heated itexpands and its level rises up the scale.

• The choice of liquid, the thinness of thebore or the size of the bulb will a $ ect thesensitivity of the thermometer.

• The choice of liquid will a $ ect the range ofthe thermometer.

Thermocouple

• A thermocouple is a junction of two di$ erent metals.

• Electrons will move across the junction creating a measurable voltage.

• The higher the temperature, the more energy the electrons will have, moreelectrons will move and we get a greater voltage.

• The voltage is then calibrated.

• High temperatures can be quickly recorded.

Heat Transfer

• Heat flows from hot areas to cold areas.

• In solids, heat moves by conduction.

• In liquids and gases ! fluids ", heat moves byconvection.

• In a vacuum heat has to move by radiation.

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Conduction

• Heat moves from particle to particle as they collide.

• Poor conductors are called insulators.

• Solids are the best conductors ! especially metals ".

• Gases are the best insulators.

HeatHeat

Questions on Conduction.

1. Why does a robin flu$ up its feathers in Winter?

2. Why is a string vest warmer than a cotton vest?

3. Design an experiment to compare conductors.

Cool fluid ina beaker.

ConvectionWarm fluidexpands and

rises. ! lowdensity "

Denser Cool

fluid sinks

Convectioncurrents

circulate theheat.

HeatHeat sourceis applied.

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Questions on Convection

• Why should you stay close to the ground in a smoke#filled room?

• Why is the heating element at the bottom of a kettle?

Radiation

Infra #redlight energy

emitted..Coolerobject

Hot object! warmer thansurroundings ".

Radiation

• Black objects are better radiators and absorbers than white or shiny objects.

• Rough objects are better radiators and absorbers thanshiny or smooth objects.

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Questions on Radiation

• Why are houses often painted white in hotcountries?

• Why do marathon runners wear an aluminiumblanket at the end of a race?

The Vacuum Flaskstopper

silversurface

vacuum

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1

Thermal PhysicsQuantity and

symbolDefinition

Symbol

equationunits

Temperature, T, !

The temperature of a gas is related to the

motion of its particles. The faster, andtherefore the more energetic the particles

the hotter the gas.

oC, K

Brownian Motion

The random, jerky motion of particles

(pollen in water, smoke in air) in a

suspension is evidence for the kinetic model

of matter. The massive particles are moved

by light, fast moving molecules.

Evaporation

The more energetic molecules escape from

the surface of a liquid. This leaves the

liquid left behind with a lower average KE,

and hence a cooler liquid.

Boyles’ Law

For a fixed mass of gas, the pressure is

inversely proportional to the volume, (at

constant temperature)

P " 1

V

PV = k

Charles’ Law

For a fixed mass of gas, the volume is

directly proportional to the temperature, (at

constant pressure)

V " T

V = k T

Pressure Law

For a fixed mass of gas, the pressure is

directly proportional to the temperature, (at

constant volume)

P " T

P = k T

Gas LawFor a fixed mass of gas, the

Pressure x Volume = a constant

Temperature

PV = kT

P1V1 = P2V2 T1 T2

Temperature

must be the

absolutetemperature

in Kelvin,K.

The other

quantities

must beconsistent.

Thermal Capacity, cThe amount of heat energy required tochange the temperature of a body by 1 oC

c = E

#TJ/

oC

Specific Heat

Capacity, c

The amount of heat energy required to

change the temperature of a unit mass of a

substance by 1oC

c = Q

m#T

J/kg oC

Jkg oC

Latent Heat, L

The amount of energy required to change

the state of a body without a change in

temperature

J

Specific Latent Heat

of Fusion, L


the state of unit mass of substance, from

solid to liquid without a change intemperature

L = Q

m

J/kg

J/g

Specific Latent Heat

of Vaporisation, L


the state of unit mass of a substance from

liquid to gas without a change intemperature

L = Q

m

J/kg

J/g

Conduction

The movement of heat energy by the

passing on of vibrations from particle to

particle.

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2

Convection

The movement of heat energy by the mass

movement of fluids, due to expansion and

density changes due to heating.

RadiationThe movement of heat energy by the form

of an electromagnetic wave. (Infrared)

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iGCSE Physics


Paper 1 Compilation

Thermal Physics

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7


14 The diagram represents molecules in a liquid.

A and C are molecules with a high amount of energy.

B and D are molecules with a low amount of energy.

Which molecule is most likely to be leaving the liquid by evaporation?

15 The size of a balloon increases when the pressure inside it increases.

The balloon gets bigger when it is left in the heat from the Sun.

Why does this happen?

A The air molecules inside the balloon all move outwards when it is heated.

B The air molecules inside the balloon are bigger when it is heated.

C The air molecules inside the balloon move more quickly when it is heated.

D The number of air molecules inside the balloon increases when it is heated.

16 What must expand in order to show the temperature rise in a mercury-in-glass thermometer?

A the glass bulb

B the glass stem

C

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