ZNOTES.

ORG

UPDATED TO 2023-2025 SYLLABUS

CAIE IGCSE
PHYSICS
CAIE IGCSE PHYSICS

1. 4000 = 4 × 10 × 10 × 10 = 4 × 10 3
2. 400 = 4 × 10 × 10= 4 × 10 2
1. Motion, Forces and Energy
All answers in this IGCSE Physics syllabus can be written in 2
or 3 signi cant gures.
1.1. Physical Quantities and
Measurement Techniques Common Length Conversions

Length: Measurements Units in meters

The metre rule can measure distances of a few 1 decimetre (dm) 10 −1 meters (m)
centimetres (cm) and the nearest millimetre (mm).
1 centimetre (cm) 10 −2 meters (m)
A tape measure will be used for measuring longer
distances. 1 millimetre (mm) 10 −3 meters (m)
Ensure the line of sight is at 90 degrees to avoid 1 micrometre (μm) 10 −6 meters (m)
parallax error. 1 nanometre (nm) 10 −9 meters (m)

Measurements Units in meters

1 kilometre (km) 10 3 meters (m)
1 gigametre (Gm) 10 9 meters (m)
Volume
A measuring cylinder can measure liquid volume and Scalar and Vector Quantities
volume change when measuring irregular objects.
(Ensure you measure from the bottom of the Scalar Vector
meniscus) ✔ magnitude, X direction ✔ magnitude, ✔ direction
Force, Weight, Velocity,
Distance, Energy,
Acceleration, Momentum,
Temperature, Speed, Time,
Electric Field Strength and
Mass
Gravitational Field Strength

Calculating Vectors (Calculation or Graphically)

If forces W and Q are acting at right angles to each other

from a point
Calculate the magnitude by using:
F = W 2 + Q2 ​

Calculate the force by using:

W
tan(x) = Q ​

Time
Clock, Digital Timers (reading to 0.1s or better) to
measure time intervals

Finding the Thickness of 1 Paper

Measure the thickness of 100 sheets of paper.

Dividing your answer by 100 will then give an accurate
gure for one sheet

Système International (SI) Units 1.2. Motion

SI Units Units Speed: the distance travelled per unit of time.
Length metre (m) Use the equation
Mass kilogram (kg) v= s
t ​

Time seconds (s) Where:

Standard Notation is always in the power of 10 v is speed (m/s)

CAIE IGCSE PHYSICS

s is displacement (m) Calculating Acceleration on Speed-Time Graphs

t is time (s)

d
AverageSpeed = t
​

Velocity: the speed in a given direction.

Distance-Time Graphs

Free Fall
Distance-Time Graphs The acceleration of free fall “ɡ” for an object near the
1 Acceleration surface of the Earth is constant and is approximately 9.8
2 At rest m/s².
3 Deceleration Do note! In free fall, there is No Air Resistance.
From 2023 onwards, the instructions will tell you to use
4 Constant Speed
9.8 m/s². This detail is very important for numerous
calculations in this chapter.

Terminal Velocity

Speed-Time Graphs

Speed-Time Graphs
1 Increasing Acceleration
2 Constant Speed
3 Decreasing Acceleration
4 Uniform Acceleration
5 Uniform Deceleration
6 Decreasing Deceleration
7 Increasing Deceleration

Acceleration
1. As speed increases, air resistance increases.
Acceleration: the change in velocity per unit of time.
2. The acceleration will decrease.
Δv
a = v−u
Δt = Δt ​ ​
3. Eventually, air resistance = weight, leading to zero
resultant force. This reaches terminal velocity.
Where:
4. When the parachute is deployed, the parachute
a is acceleration surface area increases, leading to increased air
v is the nal velocity resistance, decelerating the skydiver.
u is the initial velocity 5. As the skydiver decelerates, air resistance will
Δt is the change in time. decrease until it equals the weight. A new terminal
velocity is reached again.
The di erence between the initial and nal velocity nds the 6. At last, when it touches down, the velocity quickly
change in velocity. drops to zero.

Change in velocity = nal velocity − initial velocity

Δv = v − u 1.3. Mass and Weight
NOTE: Deceleration is the same as Negative Acceleration. Mass: a measure of the quantity of matter in an object at rest
relative to the observer. The mass of a body is a measure of
the amount of matter in it.
Weight: a gravitational force on an object that has mass.
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Gravitational eld strength g: as force per unit mass. Forces may produce changes in an object's size, shape
The equation for gravitational eld strength is : and motion.
Solid friction is the force between two surfaces that may
g=W
m
​

impede motion and produce heating.

Friction (drag) acts on an object moving through a liquid
Gravitational eld strength is equivalent to the
acceleration of free fall. or a gas (air resistance).
Weights (and masses) may be compared using a balance.
The weight of an object is the e ect of a gravitational eld Springs
on its mass.
Hooke’s Law
Weights (and masses) may be compared using a balance. Extension is directly proportional to force
This is only true if the limit of proportionality is
not exceeded
1.4. Density
The limit of proportionality is the point at which the load-
Density: mass per unit volume. extension graph becomes non-linear.
The equation for density is:
p = mv ​ Properties of Hooke’s Law

p = density The graph starts from the origin (0)

m = mass The graph is regular and in a straight line
v = volume

With this equation, you can determine the density of a liquid,

of a regularly shaped solid

Finding the Density of an Irregularly Shaped Object

Use a balance to measure the mass of the object

Find the volume using the water displacement method

Spring Constant

The spring constant k is de ned as force per unit extension.

\n Recall and use the equation:
k = Fx ​

Where:

F is the force or load (N)

x is the extension (cm)
k is the spring constant (N/m, N/cm, N/mm)

Use the formulae p = m

v
​
Forces And Resultants

Sinking Phenomenon It has magnitude and direction (vector quantity)

Usually, there is more than one force acting on the object
An object will sink in a liquid of lower density than its own
Newton’s First Law
e.g., Wood has a lower density than water, so it oats
For, steel has a higher density than water, so it sinks An object stays at rest or continues to move in a straight
line at a constant speed unless acted on by a resultant
force.
1.5. Forces
For example, if these forces were absent, an object would
A force is a push or a pull. move on forever
CAIE IGCSE PHYSICS

The lesser the external forces opposing a moving body, no resultant force
the smaller the force needed to keep it moving with clockwise = anticlockwise
constant velocity
Center of Gravity
Newton’s Second Law
Centre of Gravity: the position at which all the mass of the
F = ma object is acted at

F= force If the centre of gravity passes through the base of the

m= mass object, the object can topple
a = acceleration
Conditions for Making an Object Stable
This is the force that acts on an object going from point A
to point B Lower the centre of gravity
increase the area of the bottom
Friction

Friction is the force that opposes one surface moving or 1.6. Momentum
trying to move.
Momentum: as mass x velocity (kg m/s)
Static Friction: when the force is applied on the object at
the start, and the friction is at its highest value
The equation for momentum is p = mv
Dynamic Friction: when friction acts on the object when it Where:
moves, it is less than the maximum value.
p is momentum
m is mass
Centripetal Force v is velocity

The force that acts towards the curve's centre and keeps The resultant force is de ned as the change in momentum
a body moving in a circular path is called the centripetal per unit of time:
force.
Describe the motion in a circular path due to a force F = Δp
Δt ​

perpendicular to the motion. ∴ F = mΔv

Δt ​

In a circular motion, if speed increases, the force needed

Impulse of a force: as force x time for which force acts:
increases (mass and radius are constants).
In a circular motion, if the radius decreases, the force Impulse = F Δt = Δ(mv)
needed increases (mass and speed are constants). In a
circular motion, an increased force is required to keep The Principle of the Conservation of Momentum
speed and radius constant if mass is increased.
the direction of the force is always towards the centre of The general law of physics, according to which the quantity
the circle called momentum that characterises motion, never changes
in an isolated collection of objects; that is, the total
Moments of Forces momentum of a closed system remains constant.

Moment of a force as a measure of its turning e ect. 1.7. Energy, Work and Power
The moment of a force is de ned as Energy 'stores’ are kinetic, gravitational potential,
moment = force x perpendicular distance from pivot chemical, elastic (strain), nuclear electrostatic and
internal (thermal).
Applying the Principle of Moments Energy is transferred between stores during events and
processes.
When a body is not moving the sum of the
Energy is transferred by forces (mechanical work done),
clockwise moments about any point equals the
electrical currents (electrical work done), heating,
sum of the anticlockwise moments about the
electromagnetic, sound, and other waves.
same point. There is no resultant moment on
an object in equilibrium
The Principle of the Conservation of Energy
clockwise = anticlockwise
The principle of energy conservation states that energy is
Apply the principle of moments in situations with more
neither created nor destroyed. It may transform from one
than one force on each side of the pivot.
type to another.
Conditions for No Resultant Force
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Energy can only be used by converting it from one form to

another. Unless energy is added from the outside, a
system always possesses the same quantity of energy.
The chemical energy of the batteries is transformed into
electrical energy in a torch, which is then converted into
light and heat. This energy is either absorbed or re ected
by the environment.

Kinetic Energy Formula

Mechanical or electrical work done is equal to the energy
transferred.

The Equation for (mechanical) Work Done is:

W = F d = ΔE
Units: Joules (J)
Where:

W = Work Done
F = magnitude of the force
d = the distance in the direction of the force

Energy Resources
Change in Gravitational Potential Energy
Useful energy may be obtained, or electrical power
generated, from:
Non-Renewable Energy
Renewable Energy Sources
Sources
Fossil Fuels Wind
Oils Tidal
Coal Hydro-electric
Natural Gas Geothermal
Solar (EM Waves from the
Nuclear
sun)
- Biofuels

Some sources of energy derive their energy from the sun.

These are:
Energy Transfer Diagrams
Coal: formed from dead trees that have used energy from
the sun to produce hydrocarbons that have become coal
under pressure
Biofuels: organic matter that is burned to produce energy
Hydroelectric: energy relies on the sun’s energy to run the
water cycle so energy can be harnessed
Wind - gets heated and rises and cooler air ows to ll the
space
Solar - Electromagnetic waves from the sun are captured
by photocells and turned into energy

Sankey Diagrams Environme

Renewability Availability Reliability Scale
Impac
Wind ✓ high low high on bird
Solar ✓ high low high low impa
Almost
Geothermal ✓ low high low
impac
Biofuels ✓ high high high low impa
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Environmentalchange in pressure = density x gravitational eld strength x

Renewability Availability Reliability Scale
Impact change in depth
Hydro- impacts Δp = ρgΔh
✓ high high high
electric marine life Where:
Tidal ✓ high low low - Δp = pressure di erence in pascals (Pa)
ρ = density in kilograms per cubic metre (kg/m3)
Greenhouse
Coal ☓ high high low g = gravitational eld strength (N/kg)
gases
Δh = change in height/height of vertical column (m)
Radioactive
Nuclear ☓ low high high
substances
2. Thermal Physics
Boilers, turbines, and generators generate electricity in a
power plant.
2.1. Kinetic Model of Matter
Properties of the 3 States of Matter: The Molecular Model

E ciency

Useful energy output

Efficiency = × 100
Total energy input
​

Power

Power: work done per unit of time and energy transferred per
unit of time.
W Particles that make up matter can be made of one or
P= ​

more atoms
t
ΔE As particles of gas strike the walls of containers, their
P= ​
momentum changes and a force is created, which can be
t calculated using the following:
P = power (watt)
W = work done (J) ΔP
Fnet =
ΔE = energy transferred (J) Δt
​ ​

T = time (s)
The temperature has an Absolute Zero: -273 ℃ (Zero
Kinetic Energy)
1.8. Pressure Brownian Motion is the random motion of particles
suspended in a uid resulting from their collision with
Pressure is de ned as force per unit area and measured in fast-moving atoms or molecules in the uid.
N/m or Pa. 1 Pa = 1 N/m

The equation for pressure is: p = Fa ​

Pressure and Volume at Constant Temperature
Where: (Boyle’s Law)
p is pressure
F is force P, V, T (Constant)
1
a is area P ∝ P is inversely proportional to V
​

V
k
Pressure in Liquids P = ​

V
∴ k = PV
Pressure beneath a liquid's surface changes with the liquid's
depth and density. The equation gives the change in pressure
P1 V1 = P2 V2
​ ​ ​ ​

beneath the surface of a liquid: