Question

why it is needed to add the speed of the boy n the image in my last question? i m not satisfied with your answer . pls describe that i hope that the ans will be 2m/s at any cost. how can u chage the speed of the boy. if a boy is running towards a mirror with a speed of 2m/s then his image should also run towards the boy with the speed of 2m/s. i can't be 4m/s. hope that u will clear my all doubts as soon as possible. m waiting so pls reply me soon

Answer 1

If the boy is running at 2 m/s with respect to ground towards mirror, only the boy can see his image running towards him at 4 m/s .
With respect to ground, speed of image will be same as the speed of boy ( i.e. 2m/s).
Here, the concept of relative motion is applied
when the boy is seeing his image.
With respect to boy, he assumes himself to be at rest and so he feels that other objects in his surrounding have a speed of 2m/s(which is his actual speed) but in opposite direction of the direction of his actual speed. So According to him the image will be moving towards him with the actual speed of the image+ the speed of boy towards the boy. So, relative to the boy, image has a speed of 2+2=4m/s towards him.

But according to some other observer who is at rest, with respect to ground, the speed of image will be 2m/s.