Machine's operate by tranforming a small force applied over a long distance to a strong force applied over a short distance, enabling them to carry heavy loads when operated with weak forces.

$F$1d1 = W2d2

## Output Power

$\text{Weight of Load N} \times \text{Speed m/s}$

## Work and Energy

$\text{Work Done J} = \text{Force N} \times \text{Distance moved in Direction of the Force m}$

Energy is an objects capacity of performing work. e.g. raising an object increases its potential energy that it will unleash when it is dropped.

## Energy Stores

Forms of energy that objects may possess.

### Kinetic Energy

Energy due to motion

### Potential Energy

Energy due to position

### Elastic Energy

Energy stored through stretching and squeezing

### Electrical Energy

Energy of particles carrying electric charge

### Thermal Energy

Energy due to heat

### Nuclear Energy

Energy that can be released from an atom with an unstable nucleus

### Chemical Energy

Energy released when chemical substances undergo chemical reactions

Energy can be moved between objects and transferred from one store to another.

### Examples of Energy Transfer

• Light or soundwaved emitted by one object are absorbed by another
• Heat transfer from a hot to a cold object
• An object's potential energy becoming kinetic energy as it falls

## Conservation of Energy

The total energy of an isolated system stays the same as its objects exchange energy with each other (regardless of the systems specific state).

## Energy and Power

Power (Watts) is rate of energy transfer.

$1W = \frac{1J}{1s}$

$\text{Power} = \frac{\text{Energy Transferred}}{\text{Time Taken}}$

## Efficiency and Power

Machine's have input and output powers that are almost never equal due to energy being lost to waste heat. A machine's maximum efficiency is $1$.

$\text{Efficiency} = \frac{\text{Output W}}{\text{Input W}}$

## Kinetic Energy

$v = \text{Velocity}$
$m = \text{Mass}$

$\text{Kinetic Energy} = \frac 1 2 m v^2$

## Potential Energy

$H = \text{Gain/Loss of height}$

$\text{Potential Energy} = mgH$