Question

A 5.2 kg rock falls off of a 13 m cliff. If air resistance exerts a force of 16 N, what is the kinetic energy when the rock hits the ground?

Answer 1

Kinetic energy, E = 662.27 J

Step-by-step explanation:

Given that,

Mass of the rock, m = 5.2 kg

It is falls off of a 13 meters cliff.

Force due to air resistance, F = 16 N

To find,

The kinetic energy when the rock hits the ground.

Solution,

Initial velocity of the rock will be zero as it is at rest. Let v is the final speed of the ball. It is given by :

`v=√(2gh)`

`v=√(2* 9.8* 13)`

v = 15.96 m/s

The kinetic energy of the rock is given by :

`E=(1)/(2)mv^2`

`E=(1)/(2)* 5.2* (15.96)^2`

E = 662.27 J

So, the kinetic energy when the rock hits the ground is 662.27 J.