Question

a man stands 10 m in front of a large plane mirror . how far must he walk before he is 5 m away from his image

Answer 1

In a plane mirror, object distance = Image distance

Given Man's distance from image is to be 5 m.

This means distance of man from mirror + Distance of image from mirror = 5 m

2 x (Distance of man from mirror) = 5 m

Distance of man from mirror = 2.5 m

Initially he is 10 meters from the mirror.

So, he will have to walk (10-2.5) = 7.5 meters towards the mirror.