# Kinetic and potential energy notes.

Notes for either physics 2 or 3 - it's been a while since i did the exam so i can't remember; but they helped me :)

- Created by: Dora Eland
- Created on: 13-04-12 14:48

First 237 words of the document:

KINETICENERGY

ANYTHING WHICH IS MOVING HAS KINETIC ENERGY. THE GREATER THE MASS AND SPEED,

THE GREATER THE KINETIC ENERGY.

KINETIC ENERGY = ½ X MASS X VELOCITY2

For example: A car has a mass of 2450kg and is travelling at

38m/s. Calculate its kinetic energy.

Answer: 0.5 x 2450 x 382 = 1768900J.

To stop a car the kinetic energy has to be converted to heat energy at the brakes and

tyres: If you double the speed, you double the velocity. But because the velocity is

squared the KE will increase by a factor of four. So you need 4 times the distance to stop.

So...

i. The greater the mass and speed, the greater the KE

ii. KE = ½ x m x v2

iii. When braking, KE has to be converted into heat energy

iv. When you double your speed you quadruple your stopping distance.

POTENTIALENERGY

ELASTIC POTENTIAL ENERGY: THIS IS STORED WHEN WORK IS DONE ON AN OBJECT TO

CHANGE THE SHAPE.

E.g. springs store potential energy whenever they're compressed or stretched.

GRAVITATIONAL POTENTIAL ENERGY: THE ENERGY STORED IN AN OBJECT WHEN IT IS AT

A HEIGHT AGAINST GRAVITY.

GPE= MASS X GRAVITY X CHANGE IN HEIGHT

You have to move something to increase the GPE and that

energy is released when the object falls.

## Comments

No comments have yet been made