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Simple Machines.

Lever It is a long rod that can be used to

cut things, move heavy objects, or open tins. for example :hammer, bottle-

opener, a pair of Scissors etc.

Pulley A pulley is made up of a grooved

wheel and a rope. It is used to lift loads.Machines such as cranes and sailboats

make use of pulleys.

Wheel and AxleWheel and axle is made up of a wheel

through which a rod is called axle passes. Such

a combination helps to move objects or change their direction.

Machines such as cars, roller skates and door knobs make use of wheel and axle.

Inclined Plane

Inclined plane is used to lift heavy loads to a height easily. An inclined plane makes movement easier.

Some examples are ramp , slanted road , path up a hill , slide etc.

WEDGEA wedge is a simple machine used to push two

objects apart.A wedge is made up of two inclined planes .These planes meet and form a sharp edge.

This edge can spilt things apart. Some examples are knives, axes, forks,

nail ,etc.

Screw

A screw has ridges and is not smooth like a nail .

Screws are also used to hold objects together.

They are used in key rings , bottle caps , fountain pen caps, etc.

Interesting Facts About LeverWhenever you pick up anything heavy, your

elbow acts as the fulcrum of the lever, and your arm bone acts as the lever itself.

Natural body levers first developed in fish around 440 million years ago.

people used the lever in some form, for moving heavy stones or as digging sticks for land cultivation.

Question Time

QuestionsGive some examples of the simple

machines.Give some examples of lever ?What is a slide ? Give one example for each :a)pulley b) lever.Which machine helps in keeping

objects together?What is made of two inclined planes?What is made of a grooved wheel ?

Fill in the blanks.

----------------- is a wheel and axle. A well is a --------------.A ---------------- is made up of a grooved

wheel and a rope.Ramp is a example of ---------------Roller skates are example of

---------------Wheel barrow is an example of

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