Machines_ help_ us_ nilda

A machine is an object made up of one or more parts.It helps us to do a task,

saving time and effort.

We use machines to do diverse tasks,for example:

To move heavy objects. To go from one place to another To cut. To have a good time. To help us with household tasks

There are two types of machines: Simple machines.These are made of

very few parts.A pulley,a lever and a ramp are simple machines.

Compound machines.These are made of various simple machines joined together. A bicycle, a watch and a mixer are compound mahines.

Some machines work because they are moved by people or animals.

On the other hand, some machines need electricity or fuel to work, even though there may also be a person controlling them.

Many machines have an engine or motor to make them move.

PULLEYS A pulley is a simple machine with a grooved wheel around which a rope or chain is placed.A pulley makes it possible to lift or lower an object with less effort.

Multiple pulleys can lift very heavy objects with less effort.

LEVERS A lever is a rigid bar that is pivoted on a fixed point called a fulcrum.Force is applied to one end of the bar while an object to lift or grasp is put at the other end.This object is callled the load.A seesaw is a kind of lever.The fulcrum is the balancing point.Pliers, nutcrackers and tongs(tweezers,for example) are examples of levers.

INCLINED PLANES

An inclined plane is a ramp put at an angle to the horizontal.It is used to move heavy objects up or down to different levels.It uses less force than if we push or pull the objects directly.

The less inclined the ramp,the easier it is to move the object,slide it or make it roll.But the distance travelled is greater.

TOOLS• A tool is a machine used

by carpenters,electrician, mechanics and other workers.

• For example,carpenters use saws,hammers and staplers. Mechanics use spanners and crewdrivers.

• Some tools, such as hammers, are simple machines. Other tools, such as staples,are compound machines.