Experiment Name: · Web view1.4 Density Core • Describe an experiment to determine the...

IGCSE PHYSICS Section 1 General Physics

General PhysicsIGCSE Physics

Revision Book - Section 1

Name: _________________________________

Teacher: _________________________________

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Syllabus Content_______________________________

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Syllabus Details________________________________

1.1 Length and timeCore• Use and describe the use of rules and measuring cylinders to calculate a length or a volume

THINGS TO REMEMBER... Always align your eye with the position being measured This avoids parallax errors

• Use and describe the use of clocks and devices for measuring an interval of time

THINGS TO REMEMBER... Remember there is always a reaction time associated with using a

clock or stopwatch

Supplement• Use and describe the use of a mechanical method for the measurement of a small distance (including use of a micrometer screw gauge)

Micrometers are used to measure small distances accurately

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Micrometer

Vernier

• Measure and describe how to measure a short interval of time (including the period of a pendulum)

THINGS TO REMEMBER... For measuring short intervals of time (when each period is the

same), multiple measurements can be taken and then averaged

e.g. Period of a pendulum = Time for 10 oscillations / 10

1.2 Speed, velocity and accelerationCore• Define speed and calculate speed from total distance / total time

Symbol Definition SI unit

Vector / Scalar

Speed v or u Speed = total distance / total time m/s Scalar

• Plot and interpret a speed/time graph or a distance/time graph

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Dis

tanc

e m

Time s

Constant speedStationary

Constant speed

Distance-Time Graphs

• Recognise from the shape of a speed/time graph when a body is– at rest– moving with constant speed– moving with changing speed

Spee

d m

/s

Time s

Changing SpeedConstant speed

Changing speed

Speed-Time Graphs

At rest

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• Calculate the area under a speed/time graph to work out the distance travelled for motion with constant acceleration

Speed-Time Graphs

Area under graph = distance traveled

Spee

d m

/s

Time s

Distance A-B = ½ x v x t

Distance B-C = v x t

A

B C

• Demonstrate some understanding that acceleration is related to changing speed

Symbol Definition SI unit Vector / Scalar

Acceleration a Acceleration= change in velocity or speed / time

m/s2 Vector (for changing v)

• State that the acceleration of free fall for a body near to the Earth is constant

Acceleration of free fall near the Earth is constant

All objects near the earth fall with a constant acceleration The acceleration of free fall is NOT dependent on mass The acceleration is ~10m/s2

Supplement• Distinguish between speed and velocity

Symbol Definition SI unit

Vector / Scalar

Displacement s Distance moved in particular direction from a fixed point

m Vector

Velocity v or u Velocity = change in displacement / time m/s VectorSpeed v or u Speed = total distance / total time m/s Scalar

Speed has magnitude but no direction - SCALARVelocity has magnitude and direction - VECTOR

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• Recognise linear motion for which the acceleration is constant and calculate the acceleration

Acceleration is constant if...

A constant resultant force actso Eg.

Objects falling in a vacuum

Equations that can be used for constant acceleration...

v=u+ats=[(u+v)/2]/tv2=u2+2ass=ut+1/2at2

s=vt-1/2at2

• Recognise motion for which the acceleration is not constant

Acceleration is NOT constant if...

A varying resultant force actso Eg.

Objects falling in air. The air resistance increases with velocity so the resultant force changes

A car accelerating. As the velocity of the car increases the air resistance also increases, so the resultant force changes.

• Describe qualitatively the motion of bodies falling in a uniform gravitational field with and without air resistance (including reference to terminal velocity)

Dis

plac

emen

t / m

Time / s

Velo

city

/ m

/s

Time / s

Acc

eler

atio

n / m

/s2

Time / s

g = ~10 m/s2

IN A VACUUM

Dis

plac

emen

t / m

Time / s

Acc

eler

atio

n / m

/s2

Time / s

Acceleration zero at terminal velocity

WITH AIR RESISTANCE

Velo

city

/ m

/s

Time / s

Terminal Velocity

Straight line as velocity become constant

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u Initial velocity v Final velocity a Acceleration t Time s Displacement


1.3 Mass and weightCore• Show familiarity with the idea of the mass of a body• State that weight is a force

Weight (N) = Mass (kg) x g (N/kg)g = 10 N/kg (On the Earth)

• Weight is a force acting on objects because of gravity• Mass is related to the amount of matter• The Weight can be calculated by multiplying the mass by the strength of gravity

• Demonstrate understanding that weights (and hence masses) may be compared using a balance

SIMPLE BALANCE

A B

If Balance is in equilibrium then ….Weight of A = Weight of BMass of A = Mass of B

• Using standard masses the mass of unknown objects can be measured

Supplement• Demonstrate an understanding that mass is a property that ‘resists’ change in motion

5kg

10kg

5N

10N

a = 1m/s2

a = 1m/s2

As the mass increases…

• More force is needed for the same acceleration• The mass “resists” change in motion

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• Describe, and use the concept of weight as the effect of a gravitational field on a mass

Earth(LARGE MASS)

mass

Gravitational field

Weight

A gravitational field shows a region in which a mass will feel a force due to another mass nearby

The Earth is a very large mass so a strong gravitational field exists around it

Weight is the force acting on a mass due to the Earth’s gravitational field

1.4 DensityCore• Describe an experiment to determine the density of a liquid and of a regularly shaped solid and make the necessary calculation

Density (kg/m3) = Mass (kg)

Volume (m3)

Density (kg/m3) = Mass (kg)

Volume (m3)

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mass

No Gravitational Field

No Weight


Supplement• Describe the determination of the density of an irregularly shaped solid by the method of displacement, and make the necessary calculation

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1.5 (a) Effects of forcesCore• State that a force may produce a change in size and shape of a body

Deformation

Force

Deformation

• Plot extension/load graphs and describe the associated experimental procedure

7 6

5

4

3

2

1

0

String

7 6

5

4

3

2

1

0

7 6

5

4

3

2

1

0

No Force

10NForce

20NForce

Exte

nsio

n / m

Load / N

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• Describe the ways in which a force may change the motion of a body

Velocity increases in this direction

Before Effect of ForceApplied Force

Velocity = 0 m/s

F F

Unbalanced force

Velocity = 25 m/s No applied force Velocity = 25 m/s

Object Accelerates

No change to motion

Velocity decreases

Velocity = 0 m/s

F F

Balanced force

Velocity = 25 m/s Unbalanced force

No change to motion

Objects decelerates

F

100N100N

F

Velocity = 0 m/s

F F

• Find the resultant of two or more forces acting along the same line

2 N 5 N 3 N

2 N 2 N

Forces Resultant

0 N

2 N 5 N 6N

3 N

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Supplement• Interpret extension/load graphs

Exte

nsio

n / m

Load / N

Read off load

Measure extension

• State Hooke’s Law and recall and use the expression F = k x

7 6

5

4

3

2

1

0

String

7 6

5

4

3

2

1

0

7 6

5

4

3

2

1

0

No Force

10NForce

20NForce

Exte

nsio

n / m

force / N

Hooke’s Law: Up to the elastic limit the extension of a spring is proportional to the tension force. The constant of proportionality is called the spring constant (k)

F = kx

• Recognise the significance of the term ‘limit of proportionality’ for an extension/load graph

Exte

nsio

n / m

Load / N

Limit of proportionality

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• Recall and use the relation between force, mass and acceleration (including the direction)

Force (N) = Mass (kg) x Acceleration (m/s2)

F = maREMEMBER:

o Acceleration is a vector and so has directiono Force is a vector and so has direction

• Describe qualitatively motion in a curved path due to a perpendicular force(F = mv2/r is not required)

Tsinq

Pendulum

Perpendicular force provided by horizontal component of tension

Sun

EarthPerpendicular force provided by gravitational attraction of Sun

car

Perpendicular force provided by friction force between tires and road

Solar System

Car on a Corner

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1.5 (b) Turning effectCore• Describe the moment of a force as a measure of its turning effect and give everyday examples

15m

2N2N

15m

Moment = Turning forceMoment (Nm) = Force (N) x perpendicular distance from force to pivot (m)

Anticlockwise Moment = 2N x 15mAnticlockwise Moment = 30Nm

Clockwise Moment = 2N x 15mClockwise Moment = 30Nm

• Describe qualitatively the balancing of a beam about a pivotSupplement• Perform and describe an experiment (involving vertical forces) to show that there is no net moment on a body in equilibrium• Apply the idea of opposing moments to simple systems in equilibrium

15m

2N3N

10m

Anticlockwise Moment = 3N x 10mAnticlockwise Moment = 30Nm

Clockwise Moment = 2N x 15mClockwise Moment = 30Nm

Anticlockwise moment = Clockwise moment

OBJECT IN EQUILIBRIUM - BALANCED

1.5 (c) Conditions for equilibriumCore• State that, when there is no resultant force and no resultant turning effect, a system is in equilibrium

FOR A SYSTEM IN EQUILIBRIUM: There is no resultant force and no turning effect

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1.5 (d) Centre of massCore• Perform and describe an experiment to determine the position of the centre of mass of a plane lamina

Center of mass

Plane Lamina

Plum Line

Mass

Hang the lamina freely Hang a plum line from the position the lamina is hang from Draw a line along the plum line Repeat this procedure for another position

• Describe qualitatively the effect of the position of the centre of mass on the stability of simple objects

Stable Un-stable

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1.5 (e) Scalars and vectorsSupplement• Demonstrate an understanding of the difference between scalars and vectors and give common examples

SCALAR VECTORProperty with magnitude but no direction

Property with magnitude and direction

Example:SpeedDistancePressureAreaVolumeWork

Example:VelocityAccelerationForceDisplacement

• Add vectors by graphical representation to determine a resultant• Determine graphically the resultant of two Vectors

1.6 (a) EnergyCore• Demonstrate an understanding that an object may have energy due to its motion or its position, and that energy may be transferred and stored

Energy... cannot be created or destroyed can be transferred from one form to another can be stored in to be transferred later

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• Give examples of energy in different forms, including kinetic, gravitational, chemical, strain, nuclear, internal, electrical, light and sound

Energy Type Example

Kinetic Energy Moving objects (Car)Gravitational Potential Energy

Raised objects (Water in a dam)

Chemical Energy Energy stored in bonds (coal, oil)Strain Energy Energy due to flexing of materials (elastic band)Nuclear Energy Energy associated with atomic nuclei (Fission

reactors)Internal Energy Energy of materials – kinetic from particles moving

+ potential from bondsElectrical Energy Energy from moving charges (electricity)Light Energy Energy from Electromagnetic waves (light, IR)Sound Energy Energy due to vibrating particles (sound)

• Give examples of the conversion of energy from one form to another, and of its transfer from one place to another

Solar Energy

Photovoltaic CellElectrical Energy

Motor

Potential Energy

Kinetic Energy

• Apply the principle of energy conservation to simple examples

For any change to occur in nature energy must be transferred. Energy is not created or destroyed it is changed from one form into

another

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Chemical Energy IN(Petrol)Kinetic Energy OUT

(Movement of car)

Thermal Energy LOST(Heat)

Total energy in = total energy outChemical Energy = Kinetic Energy + Thermal Energy

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Supplement• Recall and use the expressions k.e. = ½ mv 2 and p.e. = mgh

1.6 (b) Energy resourcesCore• Distinguish between renewable and non-renewable sources of energy

Non-renewable: Energy sources that when used cannot be replaced (or at least it will take millions of years).e.g. Coal, Oil Natural gas.Renewable: Energy sources which can be used repeatedly without being used up. Solar energy, Wind, Tidal etc.

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• Describe how electricity or other useful forms of energy may be obtained from:– chemical energy stored in fuel

Coal can be burnt to release thermal energy - which heats water and makes it move – which turns a generator – which generates electricity

– water, including the energy stored in waves, in tides, and in water behind hydroelectric dams

Water stored behind a dam or tidal barrier can be allowed to flow down – this moving water turns a generator – which generates electricity

– geothermal resources

Cold water is pumped underground – the earth warms the water which rises – this moving water turns a generator – which generates electricity

– nuclear fission

Atoms are split in a nuclear reactor – this releases energy which heats water – the water moves and turns a generator – which generates electricity

– heat and light from the Sun (solar cells and panels)

Solar energy from the sun can be converted directly into electricity using a solar cell

Solar energy can also be used to heat water directly (IR)

• Give advantages and disadvantages of each method in terms of cost, reliability, scale andenvironmental impact

Energy Source

Cost Reliability Scale Environmental Impact

Chemical (Coal)

Low Reliable Large High

Hydroelectric / tidal

High initially Reliable (unless a drought)

Large High

Geothermal High initially Reliable Small LowNuclear High Reliable Large LowSolar Energy High Unreliable

(only available during the day)

Small Low

• Show a qualitative understanding of efficiency

In any energy transfer process energy is “lost” to non-useful forms.

CAR: Chemical Energy is converted to kinetic energy (useful) + Thermal energy (waste)

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Supplement• Show an understanding that energy is released by nuclear fusion in the Sun

Hydrogen-2

Hydrogen-3

Helium-4

neutron

+ENERGY

NUCLEAR FUSION IN THE SUN

In the Sun hydrogen nuclei fuse together to form helium nuclei In this process energy is released

• Recall and use the equation: efficiency = useful energy output / energy input × 100%

Efficiency = useful output energy / useful input energy

Percentage Efficiency = ( useful output energy / useful input energy ) x 100

In the transfer of energy from one form into another, there will always be losses, normally to heat energy.

The efficiency of the process tells use how much useful energy we get and how much is lost

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1.6 (c) WorkCore• Relate (without calculation) work done to the magnitude of a force and the distance movedSupplement• Describe energy changes in terms of work done• Recall and use ΔW = Fd = ΔE

Force

Distance moved

Work done (J) = Force (N) x Distance moved (m)

Work done = Energy Transferred

DW = Fd = DE

EXAMPLES OF WORK BEING DONE

A car engine does work against friction and accelerating the car When you lift an object you do work against gravity

1.6 (d) PowerCore• Relate (without calculation) power to work done and time taken, using appropriate examplesSupplement• Recall and use the equation P = E/t in simple Systems

Power (W) = Energy Transferred (J)

Time (s)

P = E/t

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1.7 PressureCore• Relate (without calculation) pressure to force and area, using appropriate examples

5kg5kg

5kg

50N 50N 50N

Low Pressure High Pressure

• Describe the simple mercury barometer and its use in measuring atmospheric pressure

The height of the mercury column relates to the atmospheric pressure

• Relate (without calculation) the pressure beneath a liquid surface to depth and to density, using appropriate examples

Pressure is dependent on the height and density of the column of water

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• Use and describe the use of a manometerGas with unknown pressure

h = Atm P – Unknown P

gr

Liquid density r

Manometer

• Recall and use the equation p = F/A

PressureForce (N)

Area (or m2)

Pressure (N/m2) = Force (N)Area (m2)

p = F / A

• Recall and use the equation p = hρg

h

Liquid columnDensity = rHeight = hAcceleration due to gravity = g

Pressure = p = rgh

r

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