Question

a ball is dropped from a height of 20m above the surface of water in lake. the refractive index of water is 4/3. a fish inside the lake, in the line of the fall of the ball, is looking at the ball. at an instant, when the ball, is 12.8m above the water surface, what is the speed of ball the fish sees?

Answer 1

h=20m
d=12.8m
=hd/2
=20×128/4/3×10
=200×7/3
=1400/3
=466.6-----