Which of the following are formulations of the second law of thermodynamics?

Answer 1

It isn't possible to change heat completely into work, with no other change taking place.

No system can convert energy from one form to another useful form with 100% efficiency.

It's not possible to transfer heat from an object at a lower temperature to another object at a higher temperature unless work is done.
APEX: Entropy of a system increases over time.

C.No system can convert energy from one form to another useful form with 100% efficiency.It's not possible to transfer heat from an object at a lower temperature to another object at a higher temperature unless work is done.It isn't possible to change heat completely into work, with no other change taking place.

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δQ = T dS (closed system, perfectly reversible process - which doesn't really exisit)

δQ < T dS (closed system, real, irreversible processes)

Rudolph Clausius:

• "Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time."

Lord Kelvin:

• "It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects."

Planck

• " Every process occurring in nature proceeds in the sense in which the sum of the entropies of all bodies taking part in the process is increased. In the limit, i.e. for reversible processes, the sum of the entropies remains unchanged."

• "The internal energy of a closed system is increased by an adiabatic process, throughout the duration of which, the volume of the system remains constant."

Constantin Carathéodory

• "In every neighborhood of any state S of an adiabatically enclosed system there are states inaccessible from S"

Answer 2

No system can convert energy from one form to another useful form with 100% efficiency.

and

Entropy of a system increases over time.

Answer 3

Heat cannot of itself pass from a colder body to a hotter body.

Answer 4

No system can convert energy from one form to another useful form with 100 % efficiency.

Entropy of a system increases over time.

APEX :)

Answer 5

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