Chapter 9, Problem 8A

A boulder is raised above the ground so that its potential energy relative to the ground is 200 J. Then it is dropped. What is its kinetic energy just before it hits the ground?

To determine

Kinetic energy of boulder just before it hits the ground.

Answer to Problem 8A

Kinetic energy will be equal to 200 J

Explanation of Solution

Given:

Potential energy relative to ground is, $PE=200\text{ J}$

Formula used:

According to energy conservation.

  $PE=KE$

Where, PE is potential energy and KE is kinetic energy.

Calculation:

According to law of conservation of energy, when boulder hits the ground then its total potential energy will convert into kinetic energy.

Therefore, $PE=KE=200\text{ J}$

Conclusion:

Therefore, kinetic energy of boulder just before hitting the ground is 200 J .