100.(D) High-quality energy is capable of performing a large amount of work,
while low-quality energy is capable of performing less work. Energy always
changes from high to low quality when work is performed. During the
change, some energy is lost in the form of heat, which cannot do work
(second law of thermodynamics). The amount of energy lost as heat is often
as high as 90% of the total energy involved. The reason that (D) is the
correct answer is because of the word “dispersed.” Dispersed energy is not
concentrated. Therefore, it is of low quality.
FREE-RESPONSE EXPLANATIONS
Question 1
10 Total Points Possible
(a) 3 points maximum
(i) Calculate the number of cubic feet of natural gas required to heat the
house for the winter. (1 point)(ii) Calculate the cost of heating the house using natural gas. (1 point)(iii) Calculate the cost of heating the house using electricity. (1 point)NOTE:
- If you do NOT show calculations, no points are awarded.
- No penalty will be assessed if you do not show units. However, you risk
setting up the problem incorrectly if you do not show units so that they
cancel properly. - If your setup is correct but you make an arithmetic error, no penalty is
assessed.