Question

A plane mirror is moved towards a stationary observer with a speed of $4m{s}^{-1}$. The speed with which his image will move towards him will be .........

• A. $2m{s}^{-1}$
• B. $4m{s}^{-1}$
• C. $8m{s}^{-1}$
• D. Zero

Answer 1

The correct option is C $8m{s}^{-1}$

For a plane mirror $v=u=x$(let)

So total distance between object and image is 2x. Hence when mirrors moves towards object at a speed v then image will move towards object at a speed 2v. According to question $v=4m{s}^{-1}$.So image will move towards object at a speed $8m{s}^{-1}$