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 ?
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.