Question

a)The frequency of a wave travelling at a speed of 500 m/s is 25 hz. Its time period will be
b)A boy standing 70 m from a high wall claps his hands. After how much time is an echo heard? (The speed of sound in air is 350 ms−1)

Answer 1

Answer:

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a) Time period = 1/frequency

= 1/25 = 0.04 s

b) Echo = 2d = Vt

= 2 × 70 = 350t

= 140 = 350t

t = 140/350 = 0.4 sec

hope it helps....

Answer 2

Hey there !

a) Time period = 1 / f = 1/ 25 s =0.04 s

b) Echo => 2d = Vt

350 × t = 70 × 2

t = 2/5 = 0.4 s