Question

The sound of an explosion on the surface of lake is heard by the boatman 100m away and the diver 100m below the point of explosion.
A ) of the 2 persons mentioned who would hear the sound first

B) give reason for your answer in (a)

Answer 1

A) For the boatman above the surface of water...

speed of sound in air = 344 m/s.

distance covered = 100 m.

time taken by sound = t sec

velocity = distance / time

 344 = 100 / t

 t  = 100 / 344

 t = 0.29 sec

Now, for the man below the surface of water.

speed of sound in water = 1533 m/s

distance covered = 100 m

time taken = t

But velocity = distance / time

     1533 = 100 / t

t   = 100 / 1533.

t  = 0.06 sec

B) So , the man under the water hear the sound of the explosion first....