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?
(i) The diver would hear the sound first.
(ii) Because the velocity of sound in water (1450 ms-1) is more than the velocity of sound in air (332 ms-1).
(iii) Time taken by sound to reach the diver would be less than t, where t is the time taken by sound to reach the boatman.