Physics IGCSE

Speed

Distance traveled per unit time.

Velocity

Change in displacement per unit time (speed in a given direction).

Acceleration

Rate of change of velocity.

Mass

Property that resists change in motion (inertia) and specifies the amount of matter.

Weight

The force of gravity acting on an object's mass.

Density

Mass per unit volume of a substance.

Force

An action that can change the motion, size, or shape of an object.

Resultant Force

The single overall force remaining when all forces acting on an object are combined.

Vector

A quantity that has both a magnitude and a direction.

Scalar

A quantity that has a magnitude only.

Terminal Velocity

The constant maximum velocity reached by a falling object when its weight equals air resistance.

Moment

The turning effect of a force about a pivot.

Principle of Moments

For an object in equilibrium, the sum of clockwise moments equals the sum of anticlockwise moments.

Limit of Proportionality

The point on a force-extension graph beyond which Hooke's Law no longer applies.

Momentum

The product of an object's mass and its velocity.

Impulse

Force multiplied by the time for which it acts (equals change in momentum).

Principle of Conservation of Momentum

The total momentum before a collision equals the total momentum after a collision in an isolated system.

Work Done

Product of a force and the distance moved in the direction of the force. It is only done when an object moves under the influence of a force.

Power

Rate at which work is done or rate at which energy is transferred.

Efficiency

The percentage of input energy or power that is converted into useful output.

Pressure

Force exerted per unit area.

Distance-Time Graph Gradient

Represents the speed of the object.

Distance-Time Graph Horizontal Line

Represents that the object is stationary.

Velocity-Time Graph Gradient

Represents the acceleration of the object.

Velocity-Time Graph Horizontal Line

Represents that the object is moving with constant speed.

Area Under a Velocity-Time Graph

Represents the total distance traveled by the object.

Condition for Terminal Velocity

Weight equals air resistance, causing zero resultant force and zero acceleration.

Centripetal Force Direction

Acts perpendicular to motion, directed toward the centre of the circular path.

Centripetal Velocity Change

Speed remains constant but velocity changes because the direction of motion constantly changes.

Hooke's Law Graph Linear Region

The straight-line section where force is directly proportional to extension.

Two conditions for equilibrium

The resultant force must be zero, and the net turning moment must be zero.

Elastic Collision Behavior

Objects collide and bounce off each other separately, conserving kinetic energy.

Inelastic Collision Behavior

Objects collide and stick together, losing some kinetic energy to thermal stores.

Law of Conservation of Energy

Energy cannot be created or destroyed, it can only be transferred between stores.

Sankey diagram arrow width

Represents the amount or proportion of energy being transferred.

Gravitational Field Strength (g)

The force per unit mass exerted by a gravitational field (approx 9.8 or 10 N/kg on Earth).

Center of Gravity

The single point on an object through which its entire weight appears to act.

To improve the stability of an object

Lower the center of gravity and widen its base.

depth and density

Pressure in a liquid increases with

Kinetic particle model of matter

Tiny particles that make up matter are always in continuous random motion.

Brownian motion

Random movement of microscopic particles in a fluid due to the collisions by the molecules of the fluid, discovered by randomly moving pollen grains in water.

exerts pressure on it.

The constant collision of air particles on the walls of the container

One degree change on the Kelvin scale is the same as

one degree change on the Celsius scale.

Internal energy

The total energy of all its particles.

Specific heat capacity

The amount of thermal energy required to raise the temperature of a unit mass of a substance by 1°C.

Absolute zero

The lowest possible temperature where particles have zero kinetic energy and stop moving, equal to 0 K or −273 °C.

0°C

The melting point of pure water at standard atmospheric pressure of 1 atmosphere is

100°C

The boiling point of pure water at standard atmospheric pressure of 1 atmosphere is

temperature of liquid, surface area of liquid, and moving air.

Rate of evaporation is affected by

higher temperature to lower temperature.

Thermal energy always flows from a region of

difference in temperature.

Net flow of thermal energy occurs only when there is a

conduction, convection, and radiation.

Heat is transferred through

how quickly thermal energy is transferred from the hotter end to the colder end.

The thermal conductivity of a material is dependent on

lattice vibrations of particles and free electron diffusion.

In metals, thermal energy is transferred through

only lattice vibrations of particles take place.

In nonmetals,

difference in density.

Convection is in fluids through convection currents due to a