Dr. C. L. Davis

Physics 298

Quiz 5

1. The displacement of a string is given by, y(x,t) = Asin(kx + ωt). The speed of the wave is:

a. 2πk/ω

b. ω/k

c. ωk

d. 2π/k

e. k/2π

Ans: b

2. A string carries a sinusoidal wave with an amplitude of 2.0 cm and a frequency of 100 Hz. The maximum speed of any point on the string is approximately:

a. 2.0 m/s

b. 4.0 m/s

c. 7.0 m/s

d. 13.0 m/s

e. unknown (not enough information is given)

Ans: d

3. To produce “beats” it is necessary to use two waves:

a. traveling in opposite directions

b. of (slightly) different frequencies

c. of equal wavelengths

d. of equal amplitudes

e. whose ration of frequencies is an integer

Ans: b

4. To raise the pitch (frequency) of a certain piano string, the piano tuner:

a. loosens the string

b. tightens the string

c. shortens the string

d. lengthens the string

e. removes some mass

Ans: b

5. A string of length L is clamped at each end and vibrates in a standing wave pattern. The wavelengths of the constituent traveling waves CANNOT be:

a. L

b. 2L

c. L/2

d. 2L/3

e. 4L

Ans: e

6. If two objects are in thermal equilibrium with each other:

a. they cannot be moving

b. they cannot be undergoing an elastic collision

c. they cannot have different pressures

d. they cannot have different temperatures

e. they cannot be falling in Earth’s gravitational field

Ans: d

7. The latent heat of fusion of water is 333 kJ/kg. This means that 333 kJ of heat energy are required to:

a. raise the temperature of 1 kg of water by 1 K

b. turn 1 kg of water to steam

c. raise the temperature of 1 kg of ice by 1 K

d. melt 1 kg of ice

e. increase the internal energy of 1 kg of water by 1 kJ

Ans: d

8. According to the first law of thermodynamics, applied to a gas, the increase in the internal energy during any process:

a. equals the heat input minus the work done on the gas

b. equals the heat input plus the work done on the gas

c. equals the work done on the gas minus the heat input

d. is independent of the heat input

e. in independent of the work done on the gas

Ans: b

9. The same energy Q enters five different substances as heat.

The temperature of 4 g of substance A increases by 4 K

The temperature of 3 g of substance B increases by 10 K

The temperature of 6 g of substance C increases by 15 K

The temperature of 8 g of substance D increases by 6 K

The temperature of 10 g of substance E increases by 10 K

Which substance has the greatest specific heat ?

Ans: A

10. The rate of heat flow by conduction through a slab does NOT depend upon the:

a. temperature difference between the opposite faces of the slab

b. thermal conductivity of the slab

c. slab thickness

d. cross-sectional area of the slab

e. specific heat of the slab

Ans: e