A fish rises vertically inside a pond with velocity and notices a bird diving downward

PHYSICS · Subjective · CBSE · Physics · Ray Optics and Optical Instruments · Ray Optics and Optical Instruments

Problem

A fish rises vertically inside a pond with velocity

4\,\text{cm s}^{-1}

and notices a bird diving downward. The bird's velocity appears to be

16\,\text{cm s}^{-1}

relative to the fish. What is the real velocity of the diving bird if the refractive index of water is

\frac43