Question

Explain which of the following are correct statements of the Second Law of Thermodynamics and which are not. a. All reversible heat engines have the same efficiency. b. An engine connected to one heat reservoir can do work on the surroundings. c. An engine connected to two heat reservoirs at different temperatures can do work on the surroundings. d. The entropy of the universe is conserved.

Answer 1

Answer:

a. False

b. False

c. True

d. False

Explanation:

The Second Law of Thermodynamics (2LT) has two principal states, one about the heat engines, and other about the entropy.

Heat engines are machines that work by converting heat at work. According to the 2LT, a machine like that can't convert all of the heat in work, some of it must be lost by the surroundings.

Thus, those machines, which is cyclic, can't have an efficiency of 100%, but, depending on the temperature, and the fluid used, it will vary, so, the letter "a" is false.

The engine must be connected to a hot heat reservoir, which will be a high temperature and will warm up the fluid, and to a cold heat reservoir, which will a low temperature and will be the deposit of the heat loss. So, the letter "b" is incorrect, and the letter "c" is correct.

According to the other statement of the 2LT, the entropy, a measure of the randomness, intends to increase in all of the systems, including the universe. So, as more unorganized is a system, as large as the entropy. So, the letter "d" is incorrect.