Question

A passenger sitting in a train moving with a constant velocity throws a ball in vertically upward direction where will the ball fall

Answer 1

The ball will fall backward

Answer 2

Therefore, the ball has the same horizontal velocity as that of the train due to inertia of motion. 
● All the bodies inside the train have the same velocity, as the train is moving with a uniform velocity. 
Ball has same horizontal velocity as that of the train. When the ball is thrown upwards, there is no horizontal force.