Question

The splash of sound was heard 5.35s after dropping a stone into a well 122.5m deep. Velocity of sound in air is​

Answer 1

Ball is dropped from a height of 122.5m

\begin{lgathered}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\end{lgathered}

timeofflight=

g

2h

=

t=

9.8

2×122.5

t=

9.8

245

=

25

t=5sec

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