The water level in a well is at a depth of 125 m. If the acceleration due to gravity is 10ms−2 and a boy gently drops a stone, he hears the sound of splash in 5.35 s. The speed of sound is ..........
A
300ms−1
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B
320ms−1
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C
368ms−1
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D
357ms−1
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Solution
The correct option is B357ms−1 Answer is D.
The time taken for the stone to hit the waterr is given as S=ut+12tat2. That is, 125=0×t+12×10×t2 So, t2=25,t=5. Therefore, the time in which the sound travels 125 m = (5.35 - 5)s = 0.33 s. Hence, the speed of sound = Distance/time = 125 m/0.33 s = 357.1 m/s. The speed of sound is 357 m/s.