Q.
A light ray is incident on a plane mirror $M$ . The mirror is rotated in direction as shown in figure by an arrows at frequency $\left(\right.\frac{9}{\pi }\left.\right)$ revolution/sec. What will be the speed of the spot on wall when angle of incident becomes $37^\circ $ given that the light reflected by the mirror is received on the wall $W$ at a distance of $10m$ .

NTA AbhyasNTA Abhyas 2020
Solution: