Question

If the total energy of the system of particles remains constant, a decrease in potential energy will lead to:
A) An increase in kinetic energy
B) A decrease in kinetic energy
C) Kinetic energy becoming zero
D) No change in kinetic energy

Answer 1

Hint: Total energy of a system basically comprises potential energy and kinetic energy. Also, the law of conservation of energy states that the total energy of an isolated system remains constant. Any decrease in one component of energy will increase the other component of energy so as the total energy remains constant.

Complete step by step solution:
It must be noted, the system in given is an isolated system although it is not mentioned. In an isolated system, there is no exchange of heat between the system and the surrounding. Now, let’s see what are the energies which sum up as total energy of the given system or any system.
Any system has basically two types of Energies:
Kinetic energy: The energy that a body has by virtue of its motion. This implies any body in motion will have kinetic energy. For example, a cricket ball when hit by a bat has kinetic energy.

Potential energy: Potential energy is defined as the energy which is conserved in a body by virtue of its position. This implies that an object which is at some height will have some potential energy conserved in it.
As we have already discussed in the hint, the total energy of an isolated system is constant. The total energy of a system is the sum of the potential energy and the kinetic energy. So, a decrease in kinetic energy will lead to increase in potential energy.

Therefore, option A is the correct option.

Note: Please remember that the magnitude of gravitational potential energy is always negative. Do remember that since the magnitude of potential energy is negative, the total energy of a system can be zero as well. Potential energy can be positive only when the force acting on it is repulsive in nature.