Sound

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1. The stretch modulus of aluminum is 6.9 E+10 N/m^2, and the density of aluminum is 2,700 kg/ m^3. What is the velocity of stretch waves in aluminum?
6,363 m/s
6,020 m/s
5,757 m/s
5,055 m/s
4,851 m/s

2. The velocity of sound in air is 331 m/s and the velocity of sound in helium 965 m/s. A gas is composed of mixture of 50% air and 50% helium by volume. What is the velocity of sound in the gas mixture?
351 m/s
370 m/s
393 m/s
425 m/s
443 m/s

3. A 25.0 cm long organ pipe is filled with air and is open at one end and closed at the other. The velocity of sound in air at 0 degrees C is 331 m/s. What is the frequency of the fourth mode?
1,550 Hz
1,759 Hz
2,317 Hz
2,720 Hz
3,171 Hz

4. A string with a mass per length of 2.0 gm/m is stretched with a force of 120 N between two points that are 0.4 m apart. The fundamental frequency of the stretched string is in tune with the frequency of the second mode of an organ pipe filled with air and open at both ends. The velocity of sound in air at 0 C is 331 m/s. What is the length of the organ pipe?
225 cm
175 cm
125 cm
108 cm
95 cm

5. An organ pipe is 80.0 cm long and is open at one end and closed at the other. The frequency of the third mode is 200 Hz higher than the frequency of the second mode. What is the velocity of sound?
300 m/s
320 m/s
340 m/s
360 m/s
380 m/s

6. An organ pipe is open at both ends. The frequency of the fourth mode is 316 Hz higher than the frequency of the third mode. If the speed of sound is 340 m/s, then what is the length of the organ pipe?
53.8 cm
59.8 cm
60.3 cm
62.8 cm
64.7 cm

7. An ambulance is generating a siren sound at a frequency of 2,400 Hz. The velocity of sound is 345 m/s. The observer is traveling at a velocity of 24.0 m/s toward the ambulance and the ambulance is traveling at a velocity of 24.0 m/s toward the observer. What is the frequency of the siren perceived by the observer?
2,100 Hz
2,250 Hz
2,430 Hz
2,550 Hz
2,759 Hz