What are the three main laws of energy?

Expert Answers
justaguide eNotes educator| Certified Educator

There are three main laws of thermodynamics that are universally applicable and can explain all phenomena related to energy, temperature and entropy.

The first law of thermodynamics states that in a closed system if there is no transfer of energy in the form of work done by the system, or movement of matter with inherent energy, the total energy of the system remains constant. For any change in total energy of a system, there has to be a transfer either into the system or out of the system. The energy in a closed system can change form but it cannot be created or destroyed.

The second law of thermodynamics states that when two systems interact there is an increase in their total entropy. This law explains why it is not possible to reverse certain phenomena.

The third law of thermodynamics states that as the entropy of a system decreases and moves towards zero, the temperature of the system approaches zero kelvin. This temperature is referred to as absolute zero and it is not possible for the temperature of an object to fall below 0 K.