Question

Identify what happens to the kinetic energy (KE) and gravitational potential energy (PE) of a rock as it falls.

KE and PE both increase.
KE and PE both decrease.
KE increases and PE decreases.
KE decreases and PE increases.

Answer 1

Answer:

KE increases and PE decreases.

Explanation:

POTENTIAL ENERGY (PE):

The potential energy of the rock depends upon the height of the rock, as given by the following formula:

P.E = mgh

Therefore, the potential energy will be highest at the initial point due to the highest height attained by rock. As the rock falls, its height will decrease as a result its potential energy will also decrease.

KINETIC ENERGY (KE):

The kinetic energy of the rock depends upon the velocity of the rock, as given by the following formula:

$K.E = \frac{1}{2}mv^2$

Therefore, the kinetic energy will be zero at the initial point due to the zero velocity of the rock. As the rock falls, its velocity will increase as a result its kinetic energy will also increase.

Hence, the correct option will be:

KE increases and PE decreases.