Which term describes a measure of energy that is unavailable to do work?

Which term describes a measure of energy that is unavailable to do work?

• A. Potential energy
• B. Thermal energy
• C. Electrical energy
• D. Entropy

Answer: (D)

Energy quality explains how much of a system’s energy can actually be used to do work. Entropy is the measure of energy that is unavailable for work. As processes occur, energy tends to spread out and become more disordered, making less of it able to do useful work. That’s why entropy tracks the portion of energy that can’t be harnessed for work. Potential energy is energy due to position and can do work when released. Thermal energy is the total internal energy related to temperature and can often be converted to work (though not perfectly). Electrical energy is energy of moving charges and can be used to perform work. None of these specifically describe the portion of energy that cannot be used to do work the way entropy does.

Energy quality explains how much of a system’s energy can actually be used to do work. Entropy is the measure of energy that is unavailable for work. As processes occur, energy tends to spread out and become more disordered, making less of it able to do useful work. That’s why entropy tracks the portion of energy that can’t be harnessed for work.

Potential energy is energy due to position and can do work when released. Thermal energy is the total internal energy related to temperature and can often be converted to work (though not perfectly). Electrical energy is energy of moving charges and can be used to perform work. None of these specifically describe the portion of energy that cannot be used to do work the way entropy does.