If Belly-flop Bernie has a potential energy of 5000J at the top, what is his kinetic energy when the potential energy reduces to 1000J?

To understand this problem, it's important to apply the principle of conservation of mechanical energy, which states that the total mechanical energy of an object remains constant if no external work is done on it. This total mechanical energy consists of both potential energy and kinetic energy.

Initially, when Belly-flop Bernie is at the top, he has a potential energy of 5000J and, assuming he starts from rest, a kinetic energy of 0J. As he descends, his potential energy decreases while his kinetic energy increases, keeping the total mechanical energy constant.

When Bernie’s potential energy decreases to 1000J, we can determine the change in potential energy. Initially, he had 5000J of potential energy and it is now 1000J, which means he has lost:

5000J - 1000J = 4000J of potential energy.

According to the conservation of energy, this lost potential energy is converted into kinetic energy. Therefore, his kinetic energy at this point will be equal to the amount of potential energy lost:

Kinetic Energy = Initial Potential Energy - Final Potential Energy Kinetic Energy = 5000J - 1000J = 4000J.

Thus, the correct answer reflects that