Question

Suppose you call out at a rocky cliff that is 550m away, and receive an echo in 3.3 seconds. What is the wavelength of the sound you created if its frequency is 210Hz?

Answer 1

Given that cliff is 550 m away

Time taken for echo to return, T = 3.3 sec

T = t1 + t2

t1 = time taken for sound to reach the cliff

t2 = time taken by echo to return to you from cliff

since both time sound have to travel same distance at same speed, So

t1 = t2

t1 + t2 = 3.3 sec

t1 = 3.3/2 = 1.65 sec

Now we know that

speed = distance/time

Speed of sound = 550/1.65 = 333.33 m/sec

Now we know that

wavelength = speed of sound/frequency

wavelength = 333.33/210 = 1.59 m

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