In this stunning demonstration, the Myth-busters fired a soccer ball at 50 mph out of a cannon on a truck riding at 50 mph in the opposite direction.
The ball just falls down as if it is free falling!! This is a consequence of the fact that in Newtonian mechanics, opposite vector quantities cancel out each other. You probably have heard that a legion times, but here’s the visual proof.
Sometimes I feel that textbooks butcher elegant concepts by excluding visuals during the explanation. But again, if one could incorporate gifs onto books the world would definitely be a better place. :)