# Physics Unit 4 Revision Notes

Some revision notes that I made for unit 4 of physics. Covers basically everything on the specification

- Created by: Rebecca Cutts
- Created on: 15-01-13 13:22

First 292 words of the document:

Physics Unit 4 Revision Notes

Further Mechanics

Momentum

Momentum is a measure of how hard it is to stop something

= mv

In any collision total momentum is constant provided no external forces act.

There are two types of collision; elastic and inelastic. In an elastic collision kinetic energy is conserved.

In an inelastic collision kinetic energy is not conserved.

Force is the rate of change of momentum.

(mv)

F = t

The change in momentum is demonstrated as the area under a force-time graph.

Circular Motion

Linear velocity is the speed an object moves in a straight line and is given by:

v = 2rf or v = 2r

t

Angular speed is the angle an object rotates through per second and is given by:

= 2f or = 2

t

By combining the above equations we can see that linear speed and angular speed are linked by the

equation v = r

For an object to move at a constant speed in a circular path there needs to be a centripetal force (The

force which acts towards the centre of the circle). The centripetal force is given by the equation:

F = mv2

r

The body is also undergoing constant acceleration because velocity changes with direction and the

body is constantly changing direction. Centripetal acceleration is given by the equations

a= v2

r or a = 2r

Simple Harmonic Motion

Simple harmonic motion is where an object oscillates to and fro on either side of a mid-point. Some

examples of oscillators include a simple pendulum, a child on a swing, a bungee jumper and a

vibrating springboard.

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