Question

Why is entropy always increasing?

Answer 1

Entropy:

The amount of thermal energy per unit temperature in a system that is not available for useful work is referred to as entropy.

Explanation:

1. Entropy is constantly increasing because every particle and atomic structure accelerates through time and space.
2. The second law of thermodynamics leads to expressions that contains inequalities.
3. The main inequality which has major outcome is Clausius inequality.
4. It is expressed as $\oint \frac{\mathrm{dQ}}{\mathrm{T}}\le 0$, here, $\mathrm{dQ}$ is heat entering the system at any point in the cycle and $\mathrm{T}$ is temperature.
5. For a reversible process, we get, $\oint \frac{\mathrm{dQ}}{\mathrm{T}}=0$. So, the property of cyclic integral is zero which results the quantity of expression has expressed a property and this property is known as entropy which is denoted by symbol $\mathrm{S}$.
6. So, the change in entropy is, $\mathrm{S}\equiv {\left(\frac{\mathrm{dQ}}{\mathrm{T}}\right)}_{\mathrm{rev}}$. So the entropy is related to second law of thermodynamics.
7. The zeroth law of thermodynamics states that if two objects are in thermal equilibrium state with a third object, then they are also in the thermal equilibrium state with each other.
8. It obeys as a basis for the validity of temperature measurement. By replacing the third object with a thermometer, the Zeroth law can be restated as two objects are in thermal equilibrium condition, if both have the equal temperature reading even if they are not in contact.

Thus, the entropy is always increasing.