UNIT 8:�MACHINES� *Machines Machines are devides which use the action of a force or convert one type of Energy into another. For example, a bicycle is a machine wich transforms human energy into Mechanical energy. Machines save us time and phy sical effort.
*Types of machine Some machines,such as pulleys,are very simple beacausethey have very few components.Other machines,such as computers,are complex beacause they have many components . Machines can be classified depending on the energy source.There are machines wich work with: *Human energy,such as a bicycle or a hammer *Water or wind,such as a watermill or a windmill *Fuel,such as a car or a gas stove *Electricity,such as a washing machine or a mobile phone
*Machines wich produce movement Many machines produce movement,such as escalators,cars or food blenders.These machines have a moter or engine.The motor converts fuel or electricalenergy into a movement.
*Thermal machines.
Thermal machines,such as heater and air conditioners produces heat or cold.
*Information-processing machines.
Information processing machines are used for communication and calculations.For example we can communicate with others using mobiles phones,and can make calculations on computers.