# (a) The stone is dropped from a tower of 500 m height into a pond of water at the base of the tower.

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(a) The stone is dropped from a tower of 500 m height into a pond of water at the base of the tower. When is the splash heard at the top? (Given g = 10 ms–2 and speed of sound = 340 ms–1).

(b) How do the sound waves cause vibrations in the eardrum of human ear?

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(a) Given,

Height of the tower, h = 500m

Time taken by stone to reach water surface from the top of the tower:

using h = ut + 1 2 gt 2

Time 1 = √ 2ℎ = √ 2×500 10 = √100 = 10

Time taken by the sound to reach the object:

using time = distance / apeed

Time t2 = 500 /340 = 1.47

Time at which splash is heard at the top:

= t1+t2=10+1.47=11.47s

(b) Sound waves are longitudinal waves which vibrate back and forth in the direction of its movement. It consists of compressions and rarefactions which results in pressure variation in the medium. This causes vibrations in the eardrum of human ear with required frequency and hence the sound becomes audib