Answer:
0 m/s
Explanation:
Let's take the direction in which the train is travelling as positive direction. Therefore:
- The velocity of the train with respect to earth is:
[tex]v_t = +15 m/s[/tex]
- The ball is thrown with speed 15 m/s in the opposite direction, so in the frame of reference of the train, its velocity is
[tex]v_b = -15 m/s[/tex]
Therefore, the velocity of the baseball in the earth's reference frame will be the algebraic sum of these two velocities, so:
[tex]v_b' = v_t + v_b = +15 + (-15) = 0[/tex]