Further momentum definitions

Angular Displacement

In circular motion, the angle turned through. Measured in radians or degrees.

Angular Velocity

The angular displacement per unit time, measured in radians or degrees per second. It is different from angular speed as it is defined in either a clockwise or anticlockwise direction.

Centripetal Acceleration

As a body follows an orbit its direction constantly changes, this produces a constantly changing velocity and the centripetal acceleration is needed to cause this change in velocity.

Centripetal Force

A force felt towards the centre of an object's orbit due to the centripetal acceleration.

Conservation of Momentum

In a closed system with no external forces the momentum of the system before an event is equal to the momentum of the system after the event.

Elastic Collision

When the kinetic energy of a system before an event is equal to the kinetic energy of the system after the event.

Impulse

The change of momentum of an object when a force acts on it. Equal to the area underneath a force-time graph.

Inelastic Collision

When the kinetic energy of a system before an event is not equal to the kinetic energy of the system after the event. The kinetic energy has been transferred to other forms.