Question

A man moves towards a plane mirror with a velocity v in a direction making an angle $\theta$ with the normal to the mirror. The magnitude of velocity of the image relative to man normal to the mirror will be :

• A. $2v$
• B. $\frac{2v}{sin\theta }$
• C. $2vsin\theta$
• D. $2vcos\theta$

Answer 1

The correct option is D $2vcos\theta$

The velocity of the man perpendicular to the mirror is given as $Vcos\theta$
The image also approaches with the same velocity towards the man.
Thus the relative velocity is given as $Vcos\theta -(-Vcos\theta )=2Vcos\theta$.