Question

If an object moves at a speed of $10m{s}^{-1}$ towards a plane mirror. Find out the speed of the image and its direction?

• A. $10m{s}^{-1}$, away from mirror
• B. $10m{s}^{-1}$, towards the mirror
• C. $2m{s}^{-1}$, away from mirror
• D. $5m{s}^{-1}$, towards the mirror

Answer 1

The correct option is B $10m{s}^{-1}$, towards the mirror

Object distance from the mirror is equal to image distance from the mirror.
This means that the distance traveled by the image is the same as the distance traveled by the object in any given interval of time. Hence, speed of the image is same as that of the object.
Also, when the object moves closer to the mirror, the image also moves closer to the mirror making the direction of its speed opposite to the image.
To conclude, image speed is the same as object speed $\left(10m{s}^{-1}\right)$, but opposite in direction i.e. towards the mirror.