Question

What happens to the sum of the ball’s kinetic energy and potential energy as the ball rolls from point A to point E? Assume there’s no friction between the ball and the ground. The sum decreases. The sum increases. The sum remains the same. The sum always equals zero.

Answer 1

The sum always remains the same, as nothing goes disappear in the universe.

Answer 2

Answer:

The sum remains the same.

Explanation:

The sum of kinetic energy and potential energy contitutes which is called Mechanical Energy. This is the total amount of energy in a system.

Because of the principle of conservation of the energy, in absence of a dissipation mechanism (such as friction) or an external work, to total amount of energy contained in a system cannot change. That's why, in this case, the sum of kinetic+potential energy remains the same.