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.

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.