Question

A ball is thrown vertically upward (relative to the train) in a compartment of a moving train (train is moving horizontally). Then, choose the correct option(s):

• A. The ball will maintain the same horizontal velocity as that of the compartment at the time of throwing.
• B. If the train is accelerating, then the horizontal velocity of the ball will be different from that of the train velocity at the time of throwing.
• C. If the ball appears to be moving backward to the person sitting in the compartment at any instant after the ball is thrown, it means that the speed of train is increasing.
• D. If the ball appears to be moving forward to the person sitting in the compartment at any instant after the ball is thrown, it means that the train is retarding.

Answer 1

Answer: (A), (C), (D)

The correct options are
A The ball will maintain the same horizontal velocity as that of the compartment at the time of throwing.
C If the ball appears to be moving backward to the person sitting in the compartment at any instant after the ball is thrown, it means that the speed of train is increasing.
D If the ball appears to be moving forward to the person sitting in the compartment at any instant after the ball is thrown, it means that the train is retarding.

Ball has only vertical acceleration, no horizontal acceleration. So its horizontal velocity is constant.