# Forces

## Key Words

Vectors - have a magnitude and direction.

Scalar - only have magnitude and no direction.

Contact force - when two objects are touching for a force to act.

Non-contact force - objects do not need to be touching for the force to act.

Interaction pair - a pair of forces that are equal and opposite and act on two interacting objects.

Mass - the amount of 'stuff' in a object.

Weight - the force acting on an object due to gravity.

Gravitational Force - the force of attaction between masses.

Resultant Force - the overall force on a point or object.

Equilibrium - when the forces on an object are balanced.

Moment - the turning effect of a force.

Levers - increase the distance from the pivot at which the force is applied.

Gears - circular discs with 'teeth' that transmit rotational effects.

Also see Motion, Force & Motion, Force & Pressure.

## EQUATION - Work Done with force

Work is done when you apply a force to move something.

Imagine you're pushing a box across the floor. If you apply force and the box moves, you're doing work. The key components are force and movement.

The amount of work done depends not just on how hard you push (force), but also on how far the box moves (distance). The formula for work (W) is:

## EQUATION - Elastic Potential Energy

If an object is being stretched or squashed, it has energy in its elastic potential energy store.

## PRACTICAL Investigating springs

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