Ball thrown in a moving train [duplicate]

A ball is thrown upward in a train moving with a constant velocity. Where will it land?

My intuition tells me that the ball will fall at my back. But my book says that it will return back to the thrower.

• Possible duplicates: physics.stackexchange.com/q/7479/2451 , physics.stackexchange.com/q/14993/2451 , and links therein. Apr 12 '14 at 16:27
• If the thrower is on the train than he is unknowingly also moving at the same speed as the train. Thus the ball that he throws will have an horizontal velocity equal to the speed of the train. It is this horizontal speed that makes the ball return in the hands of the thrower. If you were to observe the scene from the platform, you would see that the train, the passenger and the ball all move forward: the ball also has an upward velocity so it will describe a parabolic trajectory. Apr 12 '14 at 16:34
• @Harold I forgot to notice before I asked the question, the fact that there exists something called Newton's First Law Of Motion... Apr 12 '14 at 16:42
• well yes that is THE reason, I was trying to give you an intuitive picture Apr 12 '14 at 17:49
• 1) Do you mean straight upward; and if yes, 2) In whose frame of reference is the ball thrown straight up Apr 12 '14 at 17:59