Falling rocks from the top of a mountain possess potential energy as they sit at the top, and as they fall, this potential energy is converted into kinetic energy.

Here's a breakdown:

* Potential Energy: This is the energy stored in an object due to its position or configuration. The rocks at the top of the mountain have potential energy because of their height above the ground.

* Kinetic Energy: This is the energy an object possesses due to its motion. As the rocks fall, they gain speed and therefore have increasing kinetic energy.

So, while the rocks are at the top, they have potential energy. As they fall, this potential energy is transformed into kinetic energy.