Question

Energy can neither be created nor be destroyed, but it can be changed from one form to another. This law is known as:
A. Potential energy
B. Kinetic energy
C. Conservation principle
D. Conservation of energy

Answer 1

Hint: The given statement about the energy indicates towards the thermodynamic factors like it varies according to the given system, and surroundings. This statement can be related to the first law of thermodynamics, as it states that the total energy of the universe remains conserved, or constant.

Complete step by step answer:
a) First, let us discuss the first law of thermodynamics. It is considered a version of the law of conservation of energy.
b) As we know, according to the first law, in case of non-conservative forces, the system has the same amount of energy, unless it is added from the outside.
c) In this scenario, there is conversion of energy, i.e. mechanical into thermal energy, but the overall energy remains the same. The only way to use energy is to transform the energy.
d) Thus, we can say that the total energy of an isolated system remains constant, or it is conserved over time.
e) Therefore, energy can neither be created nor be destroyed, but it can be changed from one form to the another. This law is known as the law of conservation of energy.
 Therefore, the correct option is D.

Note: Don’t get confused between the conservative, and non-conservative forces. The conservation of mass relates directly to the conservation of energy, E=mc$^{2}$, in this equation, m is the mass of the object, and c represents the speed of light.