Question

A boy drops a stone in a 60m deep well. After how much time does he hear the splash if speed of sound is 340 m/s and g=10 m/s²

Answer 1

Total time taken = 3.64 seconds

Time taken to hear the splash of water = time taken by the stone to reach the water in well + time taken by the sound of splash to reach the listener

For time taken by the stone to reach the water in the well -

u = 0

s = 60 m = depth of the well

g = 10 m/s²

Using , s = ut + 1/2 gt²

=> 60 = 0 + 1/2 × 10 × t²

=> t² = 12

=> t = √12 seconds

=> t = 3.46 seconds

For the time taken by the sound of splash to reach the listener -

v = 340 m/s = velocity of sound

s = 60 m

s = vt'

=> t' = 60/340

=> t' = 0.176 seconds

Total time taken = t + t'

= 0.176 + 3.46

= 3.64 seconds