A child travelling in a train throwns

Question

A child travelling in a train throws a ball outside with a speed V. According to child who is standings on the ground , the speed of the ball is

Answer 1

Let the Train is moving on X-axis and Ball is thrown in Y-Z axis.

The vector sum of velocities of all the three axes will give you the velocity of ball with respect to the boy.

By only Knowing velocity of train you cant say about the exact velocity of ball.