(a) A boy with a mouth 5 cm wide stands 2 m away from a plane mirror. Where is his image and how wide is the image of his mouth? (b) The boy walks towards the mirror at a speed of 1 m/s. At what speed does his image approach him?

(a) The image of the boy will at the same distance as the boy from the mirror, i.e., at 2 m from the mirror. As the image is of the same size as the object, the image of his mouth will be 5 cm wide.

(b) As the boy walks towards the mirror at a speed of 1 m/s, his image will also approach the mirror at 1 m/s. So, the speed with which the image will approach him = 1 + 1 = 2 m/s