# The temperature of low pressure hydrogen is reduced from 100C to 20C. The rms speed of its molecules decreases by approximately:80% b.89% c.46%…

11.

The temperature of low pressure hydrogen is reduced from 100°C to 20°C. The rms speed of its molecules decreases by approximately:

a. 80%

b. 89%

c. 46%

d. 21%

e. 11%

12.

Which, of the following temperature changes, would show the smallest change in entropy for a pan of water on a hot plate?

1. 20°C to 30°C

2. 30°C to 40°C

3. 40°C to 45°C

4. 80°C to 85°C

a. 1

b. 1 and 2 are tied for smallest ΔS

c. 2

d. 3

e. 4

13.

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

14.

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

15.

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