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3. Spread some sugar.

4. Now move the box on the table with the help of thread.

Observation : You will face difficulty moving the box on the sugar spread on

the table.

Conclusion : More frictional force works on the table with sugar as compared

to that on the table without sugar.

3. Muscular Force : Muscular force is the force applied
using parts of the body like arms, legs, etc. For example,

when a weight lifter lifts weight, his arms and muscles
are used. Even when you lift a pencil to write or when

you pedal the bicycle, it requires muscular force.

Let’s Recapitulate

Fill in the blanks.

1. The force in which parts of the body are used is called _____________.
2. Walking on a ground needs _____________.

3. Walking on icy surface provides _____________.

4. If someone makes an effort to move an object, it is called _____________.

Work

When an object moves in the direction of the applied force, work is said to be done.
We do different types of work every day. Opening a can, the lid of a jar, cutting

paper, etc.

Simple Machines

Machines have made our life easy. For example, we can use a needle to stitch a
cloth and a knife to cut anything. These simple tools have made our daily work easy.

There are several simple machines which we use in our daily life. Let us discuss.

Lever : A lever helps us to move
something heavy with less effort or to cut

things. For example, bottle opener, pliers,
scissors, etc. Opener
Scissors

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