Mechanical Engineering - Thermodynamics - Discussion

As entropy means a degree of randomness, so increase in entropy means that there is an increase in randomness. So, useful energy is degraded or lost.

For instance, suppose a boy has his books spread all over in his room, whereas, a girl has her books arranged in order. Therefore, we may say that the boy's room has more randomness and thus more entropy. So if I ask them to give me a history book (example), then the girl will be able to give me that book more quickly than the boy. So we may also conclude that the efficiency of the girl is more than that of the boy.

Hope, you've got the concept of entropy.

Hers, dS= dQ/T.

Question is what does entropy represents (Not proportional or depends). Like the differential equation, I think it shows degradation of available energy.

The concept of Entropy mainly deals with the energy conversion (i.e. heat into work) and it's availability. This availability and non availability of the energy varies with the processes through which the system undergoes.

Here available energy is the work done (in a particular process) and non available energy is the internal energy stored in the system.

This brings a degree of randomness to the system. Thus the non availability degrades or reduces the interaction capability of the system with the surroundings. So the option "D" is the correct one.

Agreed with D option.

Answer D is correct because entropy means randomness of molecules. If the entropy will increase the degradation of energy will occur.

Thanks @Raghu.

Well explained @Raghu.

Option B is incorrect because entropy can be increased even when heat is lost (or temp is decreasing) by internal irreversibility.

Option D is correct which is well explained by Raghu.

Nice example @Raghu.

How it is?