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Throwing a ball out of the end of a moving train

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  • Throwing a ball out of the end of a moving train

    Let's say there is a train moving at 50 mph on the moon on a flat surface (say it's a perfect vacuum) and you are on the last cart where you throw a ball out the rear in the opposite direction the train is moving (directly away from it, parallel to the ground). The ball thrown is also instantaneously 50 mph. Let's also also say that there is an observer on the ground by the track not moving, and the ball was thrown just as it passed the observer. From the ground observer, would the ball appear to not move at all in the vacuum, then fall to the ground, maybe bounce up and down a few times, but never move an inch?

  • #2
    See the Mythbusters video at:

    Throwing a ball out of the end of a moving train | Physics Forums

    Another train question:

    A train leaves NY heading west at 90 mph.
    A train leaves Chicago heading east at 75 mph.
    How many people die in the head-on collision?


    • #3
      Yes, it won't move at all if you watch from the perspective of someone who is not on the train. It will look like 2 forces neutralize each other, and the ball will not be moving, it will fall on the ground (moon) and jump a few times, and that's all, if the conditions are perfect, and timings as well. While traveling last summer with db fahrplan, I saw a guy who threw a small rock in the direction of the river, which was behind us, but he couldn't reach it because the train had a high speed, and it felt that the rock didn't move at all.


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