Sound Calculations
Speed of sound in air is 340m/s
1. Calculate the frequency of a wave travelling through air with a wavelength of 2m.
2. Calculate the wavelength of a wave travelling through air with a frequency of 542Hz.
3. This table shows an octave (8) of musical notes as they appear in a scale from
middle C, which has a frequency of 262 Hz.
Note
Frequency (Hz)
C
D
E
F
G
A
B
C
262
294
330
349
392
440
494
524
a. Calculate the wavelength of middle C.
b. Refer to the table above. What is the relationship between the frequency of
middle C and the C of the next octave?
4.
a. A didgeridoo is an instrument made of a cylinder with one closed end. The
wavelength of the main note produced by an instrument of this type, is four
times the length of the cylinder. If the didgeridoo is 1m in length, and the speed
of sound in air is 340m/s, what is the frequency of the main note?
b. If the didgeridoo was 2m long, would the pitch of the main note be higher or
lower in frequency?
5. A hummingbird beats its wings at a rate of 70 wing beats per second.
a. What is the frequency in Hertz of the sound wave?
b. Assuming the sound wave travels through the air at a speed of 340m/s, what
is the wavelength of the wave?
6. Two boats are anchored 4 metres apart. They bob up and down, returning to the
same position every 3 seconds. When one is up, the other is down. There are never
any other wave crests between the boats. Calculate the speed of the waves.
(hint, the diagram is helpful).