IB Physics: Waves and Oscillations Exercises (Answer Key at End.)
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1. The speed of sound in a certain metal block is 3.00 × 103 m/s. The graph shows the amplitude (in meters) of a wave traveling through the block versus time (in milliseconds). What is the wavelength of this wave?(A) 0.5 m (D) 4.0 m
(B) 1.5 m (E) 6.0 m
(C) 3.0 m
2. A sonar device bounces waves with a frequency of 16 Hz off an object 2 km away and receives an echo in .4 s. What is the wavelength of the waves used?
(A) 6.25 m (D) 10000 m
(B) 625 m (E) 62500 m
(C) 1000 m
3. What is the wavelength of a wave with a speed of 12 m/s and a period of 0.25 s?
(A) 0.25 m (D) 24 m
(B) 1.5 m (E) 48 m
(C) 3.0 m
4. Base your answer to the following question on a standing wave with a frequency of 30 Hz that is set up on a string 6 meters in length and fixed at both ends as shown below.
The speed at which waves propagate on the string is
(A) 6 m/s (D) 100 m/s
(B) 15 m/s (E) 120 m/s
(C) 60 m/s
5. A radar station emits waves with a frequency of 110 kHz and a wavelength of 2.5 m. The waves strike an object and the station receives an echo 0.1 s after the initial emission. How far away is the object?
(A) 7.5 km (D) 27.5 km
(B) 13.75 km (E) 55 km
(C) 17.5 km
11. For a diffraction horn loudspeaker, the sound emerges through a rectangular opening. The opening of a diffraction horn has a width of 0.15 m. If the speaker emits a continuous tone with a wavelength of 0.11 m, what is the diffraction angle?
(a) 47° (c) 23° (e) 8.4°
(b) 39° (d) 12°
12. A 4.00-m long string, clamped at both ends, vibrates at a frequency of 200 Hz. If the string resonates in six segments, what is the speed of transverse waves on the string?
(a) 100 m/s (c) 267 m/s (e) 400 m/s
(b) 133 m/s (d) 328 m/s
13. A 3.00-m long string sustains a three-loop standing wave pattern. The wave speed is 100 m/s. What is the frequency of vibration?
(a) 25.0 Hz (c) 50.0 Hz (e) 100 Hz
(b) 33.0 Hz (d) 75.0 Hz
14. Determine the shortest length of pipe, open at both ends, which will resonate at 256 Hz. The speed of sound is 343 m/s.
(a) 0.330 m (c) 0.990 m (e) 1.67 m
(b) 0.670 m (d) 1.32 m / 6. The tension in a taut rope is increased by a factor of 9. How does the speed of wave pulses on the rope change, if at all?
(A) The speed remains the same.
(B) The speed is reduced by a factor of 3.
(C) The speed is reduced by a factor of 9.
(D) The speed is increased by a factor of 3.
(E) The speed is increased by a factor of 9.
7. Two children setup a “telephone” by placing a long, slender aluminum (Y = 6.9 × 1010 N/m2) bar
that has a length of 6.1-m between their two houses. To communicate, a child taps a coded message on one end. How long do the sound waves take to reach the other end? Note: the density of aluminum is 2700 kg/m3.
(A) 1.2 × 10–3 s (D) 6.3 × 10–5 s
(B) 2.4 × 10–7 s (E) 1.1 × 10–4 s
(C) 8.0 × 10–6 s
8. A bell produces sound energy at a rate of 4.00 × 10–3 W and radiates it uniformly in all directions.
What is the intensity of the wave 100.0 m from the bell?
(A) 3.18 × 10–8 W/m2 (D) 5.02 × 102 W/m2
(B) 3.14 × 10–7 W/m2 (E) 6.28 × 107 W/m2
(C) 5.02 × 10–2 W/m2
9. A train moving at a constant speed is passing a stationary observer on a platform. On one of the train cars, a flute player is continually playing the note known as concert A (f = 440 Hz). After the flute has passed, the observer hears the sound as a G which has a frequency of 392 Hz. What is the speed of the train? The speed of sound in air is 343 m/s.
(A) 26 m/s (D) 7.3 m/s
(B) 12 m/s (E) 37 m/s
(C) 42 m/s
10. Two golf carts have horns that emit sound with a frequency of 390 Hz. The golf carts are traveling
toward one another, each traveling with a speed of 9.0 m/s with respect to the ground. What
frequency do the drivers of the carts hear? The speed of sound at the golf course is 343 m/s.
(A) 390 Hz (D) 420 Hz
(B) 400 Hz (E) 430 Hz
(C) 410 Hz
15. A wave is traveling at 5.5 m/s on a string with a mass-per-unit-length of 0.082 kg/m. What is the tension in the string?
(a) 0.20 N (c) 2.5 N (e) 6.3 N
(b) 0.45 N (d) 4.4 N
16. The speed of sound in fresh water is 1482 m/s. At what temperature is the speed of
sound in helium gas the same as that of fresh water? Helium is considered a monatomic
ideal gas (γ = 1.67 and atomic mass = 6.685x10-27 kg).
(a) 313 K (c) 442 K (e) 637 K
(b) 377 K (d) 525 K
17. The sound intensity produced by a jackhammer is 1.0x101 W/m2. Determine the decibel level of the jackhammer.
(a) 120 dB (c) 140 dB (e) 100 dB
(b) 130 dB (d) 110 dB
Answer Key:
1-5: E B C E B
6-10: D A A C C
11-15: A C C B C
16-17: E B