A ball is dropped from a height of $20\, m$ above the surface of water in a lake. The refractive index of water is$\frac{4}{3}$ A fish fish inside the lake, in the line of fall of the ball, is looking at the ball. At an instant, when the ball is 12.8 m above the water surface, the fish sees the speed of ball as ($Take g = 10\,m/s^2$)