## Gravitation Notes And NCERT Solutions Of Class 9th Chapter-10 Science.

• March 15, 2021

## Exercise-10.4 Page: 141 ( Gravitation )

1. Why is it difficult to hold a school bag having a strap made of a thin and strong string?

Solution:

It is tough to carry a college bag having a skinny strap as a result of the pressure on the shoulders. This can be as the result of the pressure is reciprocally proportional to the expanse on that the force acts. The smaller the surface area, the larger is going to be the pressure on the surface. Within the case of a skinny strap, the contact expanse is extremely tiny. Hence, the pressure exerted on the shoulder is extremely huge.

2. What do you mean by buoyancy?

Solution:

The upward force possessed by a liquid on an object thatâ€™s immersed in it is referred to as buoyancy.

3. Why does an object float or sink when placed on the surface of water?

Solution:

An object float or sink when placed on the surface of water because of two reasons.

(i) If its density is greater than that of water, an object sinks in water.

(ii) If its density is less than that of water, an object floats in water.