1)What will happen when (a) a heavy body collides on a light mass at rest and (b) a light body collides on a heavy mass at rest?

(a) If a heavy body collides with a light body at rest, then the heavy body will continue to move with its initial speed and the light body will start moving with a velocity twice of the heavy body.

(b) If a light body collides with a light body at rest, then the light body will continue to move with its initial speed but in the opposite direction and the heavy body continues to be at rest.