milford
posted by sue on .
Suppose that a man throws a ball from the front of a train that is moving at 100 km/hr. If he throws the ball forward at 10 km/hr, what is the speed apparent to the man?

Assuming that the wind resistance doesn't blow the ball back in his face, he'd see the ball moving at a relative velocity of 10km/hr, regardless of the speed of the train.