Question

The fundamental frequencies for various open pipes are given in the table below.

L (cm)	f (Hz)
18	944
35	472
52	321
76	221

a) Draw a picture below depicting the fundamental displacement wave in an open tube of length L.

b) Write down an equation describing how many wavelengths the tube contains.

c) Write down an equation that relates the speed of sound, v, the length of the tube, L, and the frequency of the sound emitted, f , in the form L =

d) What straight line graph will yield the speed of sound as the slope?

e) Determine the speed of sound by plotting such a graph on graph paper.

Answer 1

Answer 2

b) f = v / Lambda = v/2L

wavelength , lambda1 = 2L = 2*18 = 36 cm


wavelength , lambda = 2L = 2*35 = 70 cm


wavelength , lambda = 2L = 2*52 = 104 cm


wavelength , lambda = 2L = 2*76 = 152 cm

c) f = v/2L

v = f*2L = 944*2*0.18 = 339.84 = 340 m/s

Answer 3

Answer 4

Answer 5

Answer 6

Answer 7

Answer 8