Question

A person runs with a speed u towards a bicycle moving away from him at the speed v. The person approaches his image in the plane mirror fixed at the rear of the bicycle with a speed of:

• A. u-v
• B. u-2v
• C. 2u-v
• D. 2(u-v)

Answer 1

The correct option is D

2(u-v)

Consider the motion of the person keeping the bicycle stationary. Hence, the person runs towards him at the speed of (u-v). Now, for a plane mirror, the image moves with the same speed as the object, but in the opposite direction, hence the image approaches the object as well with velocity -(u-v). Hence, the object approaches the image with velocity (u-v)-(u-v) =2(u-v).