Forces and Motion

Speed

Distance travelled divided by the time taken.

Distance-time graph

A graph that shows how distance changes over time.

Gradient / Slope

The steepness of a line on a graph (rise ÷ run).

Acceleration

The rate at which speed changes.

Deceleration

Slowing down (negative acceleration).

Ticker timer

A device that makes dots on paper tape to measure speed and acceleration.

Force

A push or a pull (measured in newtons).

Contact force

A force that requires objects to touch (e.g. friction).

Non-contact force

A force that acts at a distance (e.g. gravity).

Friction

A force that opposes motion when two surfaces rub together.

Gravity

The force that pulls objects towards each other.

Newton’s First Law

An object stays at rest or at constant speed unless a force acts on it.

Newton’s Second Law

Force = mass × acceleration (F = ma).

Newton’s Third Law

For every force there is an equal and opposite force.

Mass

The amount of matter in an object.

Weight

The force of gravity acting on an object.

Work

Force multiplied by distance moved in the direction of the force.

Energy

The ability to do work.

Power

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