Quiz 3 (PHYS262, Summer 2001)

August 1, 2001

1

A guitar string, of length 0.9 m, sounds in its fundamental mode at 350 Hz when plucked. What is the speed of sound in the string?

(a) 630 m/s (b) 194 m/s (c) 315 m/s (d) 388 m/s (e) 945 m/s

2

How many of the following statements regarding sound are true?

1)

Intensity is proportional to the square root of the amplitude.

2)

Perceived loudness depends on the logarithm of intensity of a sound.

3)

Most musical instruments make use of frequencies of standing waves.

4)

If you approach a sound-wave source with a higher velocity, you hear higher frequencies.

(a) Only one (b) Only two (c) Only three (d) All four (e) None

3

In order for two objects to have the same temperature, they must

(a)

be in thermal equilibrium.

(b)

be able to melt the same amount of ice in contact in a given time.

(c)

have the same amount of total energy.

(d)

expand in volume by the same amount as their temperature is raised by a unit degree.

(e)

All of the above.

4

In Fig. 1 is a $P$-$V$ (pressure-volume) phase diagram of an ideal gas. Initially the $P$-$V$ value of the ideal gas is located at point $A$ at temperature $T_A$. The gas slowly moves to point $B$. Then what is the new temperature $T_B$ of the gas at point $B$?

Figure 1: Prob 4

(a) ${3\over 2} T_A$ (b) ${5\over 2} T_A$ (c) ${15\over 4} T_A$ (d) ${4\over 3} T_A$ (e) ${9\over 4} T_A$