# Activity 10.2 Class 9 Science Gravitation

Activity 10.2 Class 9 Science Gravitation Chapter 10 #### What activity asks?

Activity 10.2 asks us to through a stone upward and see what happens.

#### Observation:

The stone comes back to us after reaching some height.

#### Explanation:

When we through a stone upward we work against the law of gravity. Thus it takes some force to throw upward. Higher the force higher is the maximum height of the stone. During this process, the velocity decreases. After some time the velocity is nil. This is the maximum height. Now gravitational force exceeds the upthrust and the stone falls freely.

#### Fact:

• We can calculate the height if we know the velocity at which the body is thrown by the following formula.

v2-u2 = 2as here v= 0, u = initial velocity; a=-9.8m/s2s= maximum height covered by the stone.

• The maximum magnitude of velocity is at the level of hand in both the motion whether upward or downward. And both are the same. For example, if we through a ball with 50km/hr upward. Then the ball will come in hand with the same speed that is 50km/hr.

Ref: Chapter 10.