A sound produced on the surface of a lake takes 4.5 s to reach a boatman. How much time will it take to reach a driver inside water at the same distance if speed of sound in water is 4.5 times the speed of sound in air?
The sound of an explosion on the surface of a lake is heard by a boatman 100 m away and by a diver 100 m below the point of explosion.
(i) Who would hear the sound first: boatman or diver?
(ii) Give a reason for your answer in part (i).
(iii) If sound takes time t to reach the boatman, how much time approximately does it take to reach the diver?