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 ? [ ]
1) 6 cm
2) 7.5 cm
3) 2.5 cm 4) 5 m
​

Answer 1

(2) 7.5cm

The distance between man and image should be 5 cm.

So distance between man and mirror= 5÷2 =2.5cm.

Initial distance between man and mirror is 10cm.

Final distance should be 2.5cm

So he travels (10-2.5)cm= 7.5 cm.