Question

A mirror is placed in X -Y plane and moving with velocity 4 m/s along its plane. An object is placed at rest in front of the mirror.The velocity of image will be

• A. 4 m/s towards the mirror
• B. 4 m/s away from mirror
• C. 8 m/s away from mirror
• D. Image will be at rest.

Answer 1

The correct option is C 8 m/s away from mirror

Let us assume that the object at rest is at the origin and x be the inital separation between the object and the mirror. The mirror is moving in the direction of the positive x-axis

Distance of the object from mirror = x

Distance of image from the mirror = x

Distance between the object and the image = 2x

Now, in 1 second, the mirror travels 4 meters away from the object

Distance of the object from mirror = x + 4

Distance of image from the mirror = x + 4

Distance between the object and the image = 2x + 8

Velocity of the image = (2x + 8) - 2x = 8 m/s

The velocity of the image is 8 m/sec away from the mirror