Sat November 10, 2012 By: Shourya Mukherjee

A fish under water observes a freely falling stone in air. If The refracting index of water is 4/3 what is the apparent acceleration of the stone as observed by the fish. Sir, please give a detailed explanation.

Expert Reply
Mon November 12, 2012
Under normal circumstances, the acceleration is 9.8m/s2 'because it's a free fall.
In water, the velocity of light reduces by 1.33 times as the refractive index of water is 4/3. So the apparent acceleration would be 1.3 times less or 9.8/1.3 = 7.36m/s2
Ask the Expert