Question

If a 0.9 kg ball is dropped from a height of 7 m, what is its kinetic energy when it hits the ground?

Answer 1

Kinetic energy,
`E_k=61.74\ J`

Step-by-step explanation:

It is given that,

Mass of ball, m = 0.9 kg

It is dropped form a height of 7 m, h = 7 m

When the ball is at certain height it will have only potential energy. As it hits the ground, its potential energy gets converted to kinetic energy as per the law of conservation of energy.

So,
`E_k=PE=mgh`

`E_k=0.9\ kg* 9.8\ m/s^2* 7\ m`

`E_k=61.74\ J`

So, the kinetic energy when it hits the ground is 61.74 Joules.