Page 4 - TYPES OF FORCES _FRICTIONAL , GRAVITATIONAL, MAGNETIC AND BOUYANT FORCES_

5. In the absence of friction, it would not be possible to light a matchstick by rubbing it on
the side of a matchbox.

 Frictional force has some disadvantages as well. These are:

1. Frictional force between two objects produces heat. Thus, frictional force produced
between the moving parts of a machine causes them to wear out due to the generated
heat.

2. Frictional force also causes the soles of our shoes and the tyres of our vehicles to wear
out.

5. GRAVITY

Gravity is the force that attracts objects to the centre of the earth. Because of
gravitational force, we are able to stay on the ground. For example, whenever we throw
a ball or a stone up in the air, it comes back to the ground after some time. This occurs
because of the gravitational force of the earth or gravity.