Question

A plane mirror is approaching you at $10cm/s.$ You can see your image in it. The image will approach you with a speed of :

• A. $5cm/s$
• B. $10cm/s$
• C. $15cm/s$
• D. $20cm/s$

Answer 1

The correct option is D $20cm/s$

In a plane mirror if the mirror moves at speed of $v$, then the image moves at a speed of $2v$.

So, in this case, as mirror is moving at a speed $10cm/s$, the image will move at a speed of $\left(2\right)\times \left(10\right)cm/s$ $=20cm/s$