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

Kinetic energy,

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,

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

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.