Ch. 11 and 12 Review Problems NAME_____________________________

1. Which one of the following waves is purely longitudinal? A) sound waves in air B) microwaves traveling through air C) radio waves traveling through vacuum D) waves on a plucked violin string E) surface waves in a shallow pan of water 2. A periodic wave is produced on a stretched string. Which one of the following properties is not related to the speed of the wave? A) frequency B) amplitude C) period D) wavelength E) tension in the string For #3-5. The displacement of a vibrating string versus position along the string is shown in the figure. The periodic waves have a speed of 10.0 cm/s. A and B are two points on the string.

3. What is the amplitude of the wave? A) 2 mm B) 4 mm C) 8 mm D) 12 mm

4. What is the wavelength of the wave? A) 3.0 cm B) 6.0 cm C) 9.0 cm D) 12 cm 5. What is the frequency of the wave? A) 0.90 Hz B) 1.1 Hz C) 1.3 Hz D) 1.7 Hz 6. A bell emits sound energy uniformly in all directions at a rate of 4.00 × 10–3 W. What is the intensity of the wave 100.0 m from the bell? A) 3.18 × 10–8 W/m2 B) 3.14 × 10–7 W/m2 C) 5.02 × 10–2 W/m2 D) 5.02 × 102 W/m2 E) 6.28 × 107 W/m2

7. Two fans are watching a baseball game from different positions. One fan is located directly behind home plate, 18.3 m from the batter. The other fan is located in the centerfield bleachers, 127 m from the batter. Both fans observe the batter strike the ball at the same time (because the speed of light is about a million times faster than that of sound), but the fan behind home plate hears the sound first. What is the time difference between hearing the sound at the two locations? Use 345 m/s as the speed of sound. A) 0.316 s B) 0.368 s C) 3.17 s D) 1.89 s

8. The intensity level by 15 engines in a garage is 100 dB. What is the intensity level generated by one engine? A) 67 dB B) 13 dB C) 44 dB D) 88 dB

9. A wave is traveling at 35 m/s on a string with a linear density of 0.082 kg/m. What is the tension in the string? A) 0.56 N B) 2.5 N C) 5.0 N D) 10 N

10. A certain string on a piano is tuned to produce middle C (f = 261.63 Hz) by carefully adjusting the tension in the string. For a fixed wavelength, what is the frequency when this tension is tripled? A) 87.21 Hz B) 151.05 Hz C) 370.00 Hz D) 453.16 Hz

11. Two traveling pulses on a rope move toward each other at a speed of 1.0 m/s. The waves have the same amplitude. The drawing shows the position of the waves at time t = 0 s. Which one of the following drawings depicts the waves on the rope at t = 2.0 s?

12. What is the wave speed if a wave has a frequency of 10 Hz and a wavelength of 4.0 m? A) 4.0 m/s B) 9.0 m/s C) 10 m/s D) 40 m/s

13. Find the first three harmonics of a string of linear mass density 2.00 g/m and length 0.600 m when it is subjected to tension of 50.0 N. A) 132 Hz, 264 Hz, 396 Hz B) 66 Hz, 132 Hz, 198 Hz C) 264 Hz, 528 Hz, 792 Hz D) none of the above

14. A barking dog delivers about 1 mW of power, which is assumed to be uniformly distributed in all directions. What is the intensity level at a distance 5.00 m from the dog? A) 61 dB B) 63 dB C) 65 dB D) 68 dB

15. A 4.00-m long string, clamped at both ends, vibrates at 2.00 × 102 Hz. If the string resonates in six segments, what is the speed of transverse waves on the string? A) 100 m/s B) 133 m/s C) 267 m/s D) 328 m/s

16. Four standing wave segments, or loops, are observed on a string fixed at both ends as it vibrates at a frequency of 240 Hz. What is the fundamental frequency of the string? A) 23 Hz B) 28 Hz C) 35 Hz D) 60 Hz

17. A string with a linear density of 0.035 kg/m and a mass of 0.014 kg is clamped at both ends. Under what tension in the string will it have a fundamental frequency of 110 Hz? A) 270 N B) 310 N C) 450 N D) 580 N