Question

Only conservative forces perform work on an object over a span of time. During this time, the total mechanical energy of the object ______.
decreases

increases continuously

remains constant

increases to a certain maximum

Answer 1

During this time, the total mechanical energy of the object remains constant.

Answer: Option C

Explanation:

The sum total of potential energy and the kinetic energy presented in the system is called mechanical energy. The total mechanical energy in the system, which represents the combined potential and kinetic energies, remains constant as long as the only force work at conservative forces, and mechanical energy is maintained on this principle.

For example, a gravity box in which we throw the ball straights up, and then leave the hand with a specific amounts of kinetic energy. In the first half of the track, there is no kinetic energy, but it has potential energy similar to kinetic energy that it had when that left our hand. When we catch that again, it has the same kinetic energy as when that left our hand. That is why gravity belongs to the category of conservative forces.