Question

A boy walks towards a mirror with a velocity of 1m/s. At what speed does the image approach him?

Answer 1

it comes at a spped of 2*1 ms=2 ms
because velocity is incident at at speed v
then it comes back it is -v sice velocity is a vector
so net=v-(-v)=2v

Answer 2

velocity of boy ($v_b$)= 1 m/s
velocity of image ($v_i$) = -1 m/s
(-ve sign is there as its direction is opposite to that of the boy)

Relative speed between boy and image = $v_b - v_i=1-(-1)=1+1=2\ m/s$

So the image will approach him at 2 m/s.