Page 146 - Active Science 5 Ebook and Activity

function. Electric iron, refrigerator and oven are examples of complex machines. Lever,
pulley and inclined plane are three simple machines. Wheel and axle, wedge and screw

are the modifications of these simple machines.

Let’s Recapitulate

Match the following.
1. Heat energy a. store water in tanks
2. Light energy b. fan

3. Mechanical energy c. sun
4. Electrical energy d. cooking food
5. Sound energy e. moving truck
6. Kinetic energy f. loudspeaker

Types of Simple Machines

Lever
A lever is a rod or bar that moves freely at a fixed point, called fulcrum, to move a load.

The force applied is called effort. The object on which work has to be done is called load.

You must have played on a see-saw in playgrounds. you sit on one side and your friend
site on the other side of the see-saw. The wooden plank on which you sit, moves at a fixed
point at the centre. Then you move up and down taking turns.

Thus, a lever helps to lift or move something with less effort. For example, if you want
to take out jam from bottle, it is easier to do so using a spoon rather than trying to do it
with your fingers.

Types of Lever
There are three types of lever. The types to lever depend upon the position of fulcrum, effort

and load.

a. Lever of first class: In this, fulcrum is between load and effort. See-saw, beam
balance, scissors, pliers and crow bar (used to lift heavy loads) are examples of the
lever of first class.

Factual Study
Scissors Greater is the distance between
L the effort and the fulcrum,
E
greater is the load that can be
moved.
Beam Balance F

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