Exam 20: Entropy and the Second Law of Thermodynamics

An inventor suggests that a house might be heated by using a refrigerator to draw energy as heat from the ground and reject energy as heat into the house. He claims that the energy supplied to the house can exceed the work required to run the refrigerator. This:

Let S_I denote the change in entropy of a sample for an irreversible process from state A to state B. Let S_R denote the change in entropy of the same sample for a reversible process from state A to state B. Then:

A Carnot heat engine runs between a cold reservoir at temperature T_L and a hot reservoir at temperature T_H. You want to increase its efficiency. Of the following, which change results in the greatest increase in efficiency? The value of $\Delta$ T is the same for all changes.

A force of 5 N stretches an elastic band at room temperature. The rate at which its entropy changes as it stretches is about:

For all adiabatic processes:

Is it possible to transfer energy from a low-temperature reservoir to a high-temperature reservoir?

For one complete cycle of a reversible heat engine, which of the following quantities is NOT zero?

According to the second law of thermodynamics:

Let k be the Boltzmann constant. If the configuration of the molecules in a gas changes so that the multiplicity is reduced to one-third its previous value, the entropy of the gas changes by:

Consider the following processes: The temperatures of two identical gases are increased from the same initial temperature to the same final temperature. Reversible processes are used. For gas A the process is carried out at constant volume while for gas B it is carried out at constant pressure. The change in entropy:

An ideal gas, consisting of n moles, undergoes an irreversible process in which the temperature has the same value at the beginning and end. If the volume changes from V_i to V_f, the change in entropy is given by:

A Carnot engine operates with a cold reservoir at a temperature of T_L = 400 K and a hot reservoir at a temperature of T_H = 500 K. What is the net entropy change as it goes through a complete cycle?

A Carnot cycle heat engine operates between 400 K and 500 K. Its efficiency is:

In a reversible process the system:

A certain heat engine draws 500 cal/s from a water bath at 27 $\degree$ C and transfers 400 cal/s to a reservoir at a lower temperature. The efficiency of this engine is:

Consider all possible isothermal contractions of an ideal gas. The entropy of the gas:

An ideal gas, consisting of n moles, undergoes a reversible isothermal process during which the volume changes from V_i to V_f. The change in entropy of the thermal reservoir in contact with the gas is given by:

The maximum theoretical efficiency of a Carnot engine operating between reservoirs at the steam point and at room temperature is about:

One mole of an ideal gas expands reversibly and isothermally at temperature T until its volume is doubled. The change of entropy of this gas for this process is:

A heat engine that in each cycle does positive work and loses energy as heat, with no heat energy input, would violate: