Question

15.
A boy stands at a certain distance from a cliff. He claps his hands and hears
the echo (sound reflected by cliff) after 0.2s. Calculate the velocity of sound if he stands 30m away from the cliff​

Answer 1

Answer:

300 m/s

Explanation:

He claps and hears, in this time period sounds goes to the cliff from him   and   then returns to him from the cliff.

 Sound travelled the same distance twice.   If the distance between the boy and cliff is 30m  then the sound travels 2*30m = 60 m.

Using, speed = distance/time

    ⇒ velocity = 60/0.2

                       = 300 m/s

Answer 2

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A boy stands at a certain distance from a cliff. He claps his hands and hears the echo (sound reflected by cliff) after 0.2s. Calculate the velocity of sound if he stands 30m away from the cliff .

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Since the echo is reflected from the cliff 30 m away . Therefore , the $\bf{Sound_{(clap)}}$ travels a total distance of Twice the Boy's distance from the cliff , i.e

Total path covered by the echo »»

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ㅤㅤㅤㅤㅤㅤㅤㅤㅤ= 60 metre

$\because$ We know that ,

$\implies \sf{v\:=\: \dfrac{d}{t}}$

$\implies \sf{speed \:=\: \dfrac{distance}{time}}$

$\implies \sf{ velocity ( v ) \:=\: \dfrac{60}{0.2}}$

$\implies \sf{ velocity ( v ) \:=\: \dfrac{60 × 10}{0.2 × 10}}$

$\implies \sf{ velocity ( v ) \:=\: \dfrac{600}{2}}$

$\implies \sf{ velocity ( v ) \:=\: 300}$

$\therefore$ Velocity of the sound = 300 m/s

ㅤㅤㅤ

ㅤㅤㅤ꧁ ʙʀᴀɪɴʟʏ×ᴋɪᴋɪ ꧂