1. The force stretching the D string on a certain guitar is 135 N. The string's linear mass density is 0.007 kg/m. What is the speed of the waves on the string?
2. The coldest and hottest temperatures ever recorded in Switzerland are -43.2°F (231 K) and 106.7°F (315 K), respectively. What is the speed of sound in air at each temperature?
at -43.2°F at 106.7°F
3. A 860-Hz sound travels through pure argon. The wavelength of the sound is measured to be 0.37 m. What is the speed of sound in argon?
4. What frequency of sound traveling in air at 20°C has a wavelength equal to 1.8 m, the average height of a person?
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5. What is the wavelength (in mm) of 2.5 million Hz ultrasound as it travels through human tissue?
6. The huge volcanic eruption on the island of Krakatoa, Indonesia, in 1883 was heard on Rodrigues Island, 4,782 km (2,970 miles) away. How long did it take (in seconds) for the sound to travel to Rodrigues? (Assume the air temperature is 20°C.)
7. A steel cable with total length 29 m and mass 110 kg is connected to two poles. The tension in the cable is 3,234 N, and the wind makes the cable vibrate with a frequency of 2 Hz. Calculate the wavelength of the resulting wave on the cable.
8. A geologist is camped 6,474 m (about 4 miles) from a volcano as it erupts.
(a) How much time elapses before the geologist hears the sound from the eruption? (Assume the air temperature is 20°C.)
(b) How much time does it take the seismic waves produced by the eruption to reach the geologist's camp, assuming the waves travel along the surface through granite as sound waves do? (Assume the granite temperature is 20°C.)
9. A person stands at a point 234 m in front of the face of a sheer cliff. If the person shouts, how much time will elapse before an echo is heard? (Assume the speed of sound is 344 m/s.)
10. The sound level measured in a room by a person watching a movie on a home theater system varies from 40 dB during a quiet part to 60 dB during a loud part. Approximately how many times louder is the latter sound? (enter only a number as your answer)
11. Give an example of a wave that does not need a medium in which to travel and a wave that does need a medium.
12. The speed of an aircraft is sometimes expressed as a Mach number: Mach 1 means that the speed is equal to the speed of sound. If you wish to determine the speed of an aircraft going Mach 2.2, for example, in meters per second or miles per hour, what additional information do you need?
13. If you were actually in a battle fought in space like the ones shown in science fiction movies, would you hear the explosions that occur? Why or why not?
14. A low-frequency sound is heard, and then a high-frequency sound is heard. Which sound has a longer wavelength? A low-frequency sound. A high-frequency sound.
15. A person riding on a bus hears the sound from a horn on a car that is stopped.What is different about the sound when the bus is approaching the car compared to when the bus is moving away from the car?