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?
Initially,
Man and the mirror distance= 10m.
Man and his image distance= 10+10=20m
Now, New distance between the man and his image= 5 m when the distance between man and mirror is 2.5 m.
Therefore, distance he has to walk towards the mirror = 10 m - 2.5m = 7.5 m.