Physics

# Problems

PhysicsProblems

### 14.1Speed of Sound, Frequency, and Wavelength

25.
A bat produces a sound at $17 comma 250 Hz$ and wavelength $0.019 m$. What is the speed of the sound?
1. $1.7 times 10 Superscript 6 Baseline m slash s$
2. $8.6 times 10 Superscript 5 Baseline m slash s$
3. $1.15 times 10 Superscript negative 6 Baseline m slash s$
4. $3.28 times 10 squared m slash s$
26.
A sound wave with frequency of $80 Hz$ is traveling through air at $0 Superscript ring Baseline upper C$. By how much will its wavelength change when it enters aluminum?
1. $68 m$
2. $64 m$
3. $4 m$
4. $60 m$

### 14.2Sound Intensity and Sound Level

27.

Calculate the sound intensity for a sound wave traveling through air at 15° C and having a pressure amplitude of 0.80 Pa. (Hint—Speed of sound in air at 15° C is 340 m/s .)

1. 9.6×10−3 W / m2
2. 7.7×10−3 W / m2
3. 9.6×10−4 W / m2
4. 7.7×10−4 W / m2
28.
The sound level in dB of a sound traveling through air at $0 Superscript ring Baseline upper C$ is $97 dB$. Calculate its pressure amplitude.
1. $4.3 Pa$
2. $0.20 Pa$
3. $0.04 Pa$
4. $2.1 Pa$

### 14.3Doppler Effect and Sonic Booms

29.
An ambulance is moving away from you. You are standing still and you hear its siren at a frequency of $101 Hz$. You know that the actual frequency of the siren is $105 Hz$. What is the speed of the ambulance? (Assume the speed of sound to be $331 m slash s$.)
1. $17.07 m slash s$
2. $16.55 m slash s$
3. $14.59 m slash s$
4. $13.1 m slash s$
30.
An ambulance passes you at a speed of $15.0 m slash s$. If its siren has a frequency of $995 Hz$, what is difference in the frequencies you perceive before and after it passes you? (Assume the speed of sound in air is $331 m slash s$.)
1. $47.0 Hz$
2. $43.0 Hz$
3. $94.9 Hz$
4. $90.0 Hz$

### 14.4Sound Interference and Resonance

31.
What is the length of an open-pipe resonator with a fundamental frequency of $400.0 Hz$? (Assume the speed of sound is $331 m slash s$.)
1. $165.1 cm$
2. $82.22 cm$
3. $20.25 cm$
4. $41.38 cm$
32.
An open-pipe resonator has a fundamental frequency of $250 Hz$. By how much would its length have to be changed to get a fundamental frequency of $300.0 Hz$? (Assume the speed of sound is $331 m slash s$.)
1. $77.32 cm$
2. $44.09 cm$
3. $32.16 cm$
4. $11.03 cm$