1.
The temperatures TC of the cold reservoirs and the temperatures TH of the hot reservoirs for four Carnot heat engines are
engine 1: TC = 400K and TH = 500K
engine 2: TC = 500K and TH = 600K
engine 3: TC = 400K and TH = 600K
engine 4: TC = 600K and TH = 800K
Rank these engines according to their efficiencies, least to greatest.
a. 1, 2, 3, 4
b. 1 and 2 tie, then 3 and 4 tie
c. 2, 1, 3, 4
d. 1, 2, 4, 3
e. 2, 1, 4, 3
2.
An object hangs from a spring balance. The balance indicates 30N in air and 20N when the object is submerged in water. What does the balance indicate when the object is submersed in a liquid with a density that is half that of water?
a. 20N
b. 25N
c. 30N
d. 35N
e. 40N
3.
Water flows through a cylindrical pipe of varying cross section. The velocity is 3.0m/s at a point where the pipe diameter is 1.0 cm. At a point where the pipe diameter is 3.0 cm, the velocity is:
a. 9m/s
b. 3m/s
c. 1m/s
d. 0.33m/s
e. 0.11m/s
4.
A Carnot engine runs between a hot reservoir at Th and a cold reservoir at Tc. If one of the temperatures is either increased or decreased by 3.5 K, which of the following changes would increase the efficiency by the greatest amount?
a. increasing Th
b. increasing Tc
c. decreasing Th
d. decreasing Tc