1. The temperature at the base of a mountain is 10o C, what is the speed of sound at
the summit, if the air temperature is 18.3o C cooler? (3 marks)
2. Air temperature is -25o C. How long will it take sound from an explosion to travel 2.6 km?
(3 marks)
3. An air craft can fly at Mach 1.8 when the air temperature is 20o C. What is it's speed in km/h
at sea level and temperature 20o C? (4 marks)
4. A banjo is being played in a room that has an air temperature of 24o C. The frequency of the
note played is 440 Hz. What is the wavelength of the sound? (3 marks)
5. A submarine is under water when a destroyer which wants to blow it up uses sonar to locate
it. The sonar signal travels at a speed of 1480.0 m/s in the water, and returns to the destroyer
in a time of 0.54 s. How deep is the submarine? (3 marks)
6. Sound from an air plane moves from warm air of temperature 4o C into cold air below at a
temperature of -23o C. If the angle of incidence at the boundary between the layers of air is
30o, what is the angle of refraction? (4 marks)
7. A sound of frequency 360.00 Hz causes 50.00 beats to be counted in 60.00 s when a second
sound is produced.
a) What are the possible frequencies of the second sound? (4 marks)
b) If a third sound of frequency 380 Hz is produced with only the first sound present, what
is the resulting beat frequency? (2 marks)
8. A string has a tension of 260 N on it to produce a sound of frequency 320 Hz. The density of
the string is 8.36 g/cm3. If this string is replaced with a string of density 9.75 g/cm3
a) what is the new frequency of the string? (2 marks)
b) what must be the new tension in the new string to produce the original
frequency? (2 marks)
9. A pipe organ produces a note of frequency 440 Hz by using a closed pipe. The speed of the
sound in the room is 345 m/s,
a) What is the 3rd resonant length of the pipe? (2 marks)
b) If an open pipe was used instead, and we wanted a 2nd resonant length, how long is
the pipe? (2 marks)
10. A train is traveling towards you at a speed of 80.7 km/h when it blows its horn of frequency
370 Hz. The air temperature is 24o C.
a) What is the frequency of the sound reaching you before the train passes, if you are not
moving? (3 marks)
b) What is the frequency of the sound reaching you after the train passes, if you are not
moving? (2 marks)
c) If you were driving in your convertible at 110.3 km/h towards the train, while the train
is moving at 80.7 km/h towards you, what is the frequency of the sound you hear
before the train passes? (3 marks)
November 22, 2013