Question

The ripples in a certain groove 10.5 cm from the center of a 3313-rpm phonograph record have a wavelength of 2.40 mm . What will be the frequency of the sound emitted? Express your answer to three significant figures and include the appropriate units.

Answer 1

Linear velocity V = r x

where   is angular velocity

= 2 / T rad/sec
Period T = 1/rpm X 60 seconds per minute.
Period T= (1 / 33.13) x 60 = 1.81 seconds.

So angular velocity = 2 / 1.81 = 3.469 radians per second.

V =rX = 10.5cm X 3.469 rad/sec = 36.4 cm per second.

Then Frequency becomes: f = v / = 364 mm/sec / 2.4mm = 151.66 Hz....