Question

If an object moves towards a plane mirror with a speed v at an angle $\theta$ to the perpendicular to the plane of the mirror, find the relative velocity between the object and the image.

• A. v
• B. 2v
• C. 2v$\cos \theta$
• D. 2v$\sin \theta$

Answer 1

The correct option is C 2v$\cos \theta$

The correct option is C

Given,

$velocity=v$

$angle=\theta$

The image will move towards the plane mirror with - v velocity . The - sign indicates that the image moves in opposite direction of the object.
Well, if you ask the velocity of object relative to the object then it would be - 2v. It means that the object would experience that the image is moving towards it with velocity 2v.

Since the object is moving horizontal direction so the component of the velocity is $2vcos\theta$