Question

a splash heard 5.35 sec after a stone is dropped in to a well 122.5 m deep. the velocity of the sound in air is ?

Answer 1

Ball is dropped from a height of 122.5m

$time \: of \: flight = \sqrt{ \frac{2h}{g} } = \\ \\ t = \sqrt{ \frac{2 \times 122.5}{9.8} } \\ \\ t = \sqrt{ \frac{245}{9.8} } = \sqrt{25} \\ \\ t = 5 \: sec$

Time after which splash was heard = 5.35 second.

So the ball takes 5 second to reach the water in the well. When it strikes the water, a splash sound is created. The sound is heard above after 5.35s of dropping the ball.

So time taken by sound to travel 122.5 m = 5.35 - 5 = 0.35 second.

Speed of sound = distance/time = 122.5/0.35 = 350 m/s

Speed of sound in air is 350 m/s