PHYSICS Paper 2:

Force

Mass multiplied by acceleration (F = ma).

Unit of force

Newtons (N).

Vector quantity

A quantity that has both magnitude and direction.

Scalar quantity

A quantity that has magnitude only, without direction.

Weight formula

Weight = mass × gravitational field strength.

Unit of weight

Newtons (N).

Gravitational field strength on Earth (g)

9.8 N/kg.

Newtonmeter

A device used to measure weight.

Difference between mass and weight

Mass is the amount of matter; weight is the force due to gravity.

Contact force

A force that requires objects to be touching.

Example of a contact force

Friction.

Non-contact force

A force that acts at a distance.

Example of a non-contact force

Gravitational force.

Resultant force

A single force that has the same effect as all forces acting together.

Newton's First Law

An object remains at rest or moves at constant speed unless acted on by a resultant force.

Newton's Second Law

Force = mass × acceleration.

Newton's Third Law

For every action, there is an equal and opposite reaction.

Work done formula

Work = force × distance.

Unit of work done

Joules (J).

Speed formula

Speed = distance / time.

Unit of speed

Metres per second (m/s).

Acceleration formula

Acceleration = change in velocity / time.

Unit of acceleration

m/s².

Flat line on a distance-time graph

Represents a stationary object.

Straight, sloped line on a distance-time graph

Represents constant speed.

Curved line on a distance-time graph

Represents changing speed (acceleration).

Gradient of a velocity-time graph

Shows acceleration.

Area under a velocity-time graph

Shows distance travelled.

Factors affecting braking distance

Speed, road conditions, tyre condition, brakes.

Factors affecting thinking distance

Reaction time, distractions, drugs, alcohol.

Stopping distance

Thinking distance + braking distance.

Terminal velocity

The maximum speed reached when weight is balanced by air resistance.

Inertia

The tendency to remain in the same state of motion.

Larger resultant force effect

Causes greater acceleration.

Safety features that increase stopping time

Seat belts, airbags, crumple zones.

Momentum dependency

Depends on mass and velocity.

Momentum formula

Momentum = mass × velocity.

Unit of momentum

kg·m/s.

Principle of conservation of momentum

Total momentum before = total momentum after.

Impulse effect

Causes a change in momentum.

Hooke’s Law

Force = spring constant × extension (F = kx).

Unit of spring constant

N/m.

Elastic deformation

Object returns to original shape when force is removed.

Inelastic deformation

Object is permanently deformed.

Elastic potential energy formula

E = ½ × k × e².

Unit for elastic potential energy

Joules (J).

Balanced object condition

When the resultant force and moment are zero.

Moment

Turning effect of a force.

Moment formula

Moment = force × distance (perpendicular).

Wave definition

A disturbance that transfers energy from one place to another.

Unit of frequency

Hertz (Hz).

Wave speed formula

Wave speed = frequency × wavelength.

Unit of wavelength

Metres (m).

Unit of wave speed

Metres per second (m/s).

Transverse wave definition

A wave where oscillations are perpendicular to the direction of travel.

Example of a transverse wave

Light waves.

Longitudinal wave definition

A wave where oscillations are parallel to the direction of travel.

Example of a longitudinal wave

Sound.

Compression in a longitudinal wave

Region where particles are close together.

Rarefaction in a longitudinal wave

Region where particles are spread out.

Frequency definition

The number of waves per second.

Amplitude definition

The maximum displacement from the rest position.

Measuring wavelength on a diagram

Distance from one crest to the next (or trough to trough).

Larger amplitude meaning

Indicates greater energy.

Wave speed when frequency increases and wavelength is constant

Wave speed increases.

Reflection definition

When a wave bounces off a surface.

Refraction definition

Bending of a wave as it enters a new medium.

Diffraction definition

Spreading of waves as they pass through a gap or around obstacles.

Effect on light entering a denser medium

It slows down and bends toward the normal.

Normal line in reflection/refraction

An imaginary line at 90° to the surface.

Angle of incidence definition

Angle between the incident ray and the normal.

Angle of reflection definition

Angle between the reflected ray and the normal.

Law of reflection definition

Angle of incidence = angle of reflection.

Total internal reflection definition

When a wave is completely reflected within a medium.

Condition for total internal reflection

When angle of incidence is greater than the critical angle.

Device using total internal reflection

Optical fibres.

Part of the ear detecting sound waves

Cochlea.

Ultrasound definition

Sound with frequency above 20,000 Hz.

Infrasound definition

Sound with frequency below 20 Hz.

Ultrasound in medicine

Imaging internal organs and unborn babies.

Ultrasound in industry

Detecting flaws in materials.

Electromagnetic spectrum definition

Range of all types of EM waves.

Order of EM spectrum (lowest to highest frequency)

Radio, microwave, infrared, visible, UV, X-ray, gamma.

EM wave with the longest wavelength

Radio waves.

EM wave with the highest frequency

Gamma rays.

EM wave with the most energy

Gamma rays.

Microwaves use

Cooking and satellite communication.

Infrared radiation use

Heating and night vision.

UV radiation use

Fluorescent lamps and sterilisation.

X-rays use

Medical imaging.

Gamma rays use

Cancer treatment and sterilising medical equipment.

Dangers of UV radiation

Skin cancer and eye damage.

Dangers of X-rays and gamma rays

Can cause cell mutation and cancer.

Visible light use

Seeing and communication (e.g., fibre optics).

Speed of EM waves in a vacuum

3 × 10⁸ m/s.

Wave equation for EM waves

Speed = frequency × wavelength.

Type of wave are EM waves

Transverse.

Do EM waves require a medium?

No.

Ionising EM waves

UV, X-rays, and gamma rays.

Two types of magnets

Permanent and induced magnets.