A ball is thrown straight up by a passenger in a train that is moving what a constant velocity. Where would the ball land —back in his hands, in front of him, or behind him?
Does your answer change if the train is accelerating in the forward direction? if yes, how?
back in his hands. It has the same horizontal velocity as the train has (ignoring air drag of course)
Of course if the train speeds up while the ball is in the air, that changes it, but you can figure that out.