Sound produced by a bell at the bottom of a swimming pool is heard by a boy standing at the edge of the pool directly above the bell. The depth of water is 5m.
(i) Taking the speed of sound in water to be 1480m/s, calculate the time taken by the sound to reach the boy’s ear through the water.
(ii) Suppose the same bell is lifted out of the water and rung in air at 20∘C directly beneath the boy’s ear at the same distance of 5m. If the speed of sound in air at this temperature is 343m/s, calculate the time taken now.
(iii) How much earlier does the boy hear the bell when the sound travels through water compared to when it travels through air?