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B Jumping vertically on a moving train...

  1. Mar 6, 2016 #1
    I'm clueless when it comes to physics, so forgive me if this sounds stupid. But fot years I've wondered something, and no one seems to have an answer for it.

    If you are standing inside a moving bus or train, and you jump on the spot (straight up,not in the direction that the vehicle is moving) then how come you land on the same bit of flooring that you started on? The vehicle is moving, so shouldn't it have left you behind slightly,thus you land further down the vehicle?? If that makes sense? Someone enlighten me please
     
  2. jcsd
  3. Mar 6, 2016 #2

    russ_watters

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    Welcome to PF!

    This is Newton's first law:
    https://en.wikipedia.org/wiki/Newton's_laws_of_motion
    Or more broadly, the Principle of Relativity:
    https://en.wikipedia.org/wiki/Galilean_invariance
     
  4. Mar 6, 2016 #3

    davenn

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    no ... think about it a moment before I give an answer

    what is the immediate relationship between you, everything else in the vehicle and the vehicle ?

    your same Q could be asked for when you jump up off the ground (up off the earth)
    after all it's rotation speed is much faster .... equatorial speed of 465.1 m/s, 1,674.4 km/h or 1,040.4 mph


    Dave
     
  5. Mar 6, 2016 #4

    davenn

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  6. Mar 6, 2016 #5
    Thanks for taking the time to reply guys. But let me stress something. I'm thick as s**t. So russ watters I'm afraid that went over my head a bit... could you explain a bit simpler please mate. Much appreciated
     
  7. Mar 6, 2016 #6

    A.T.

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    Movement is relative. The vehicle is not moving relative to you.
     
  8. Mar 6, 2016 #7

    davenn

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    You, everything in it and the train, bus etc are moving at the same speed

    That's what I wanted you to figure out

    So when you jump up, you are still moving at that speed, there is nothing to slow you down,
    so you end up landing in the same place you jumped from
     
  9. Mar 6, 2016 #8
    Right ok I think I get it...So say if you were on the roof of the train as opposed to inside,and you jumped..you wouldn't land on the same spot then would you?
     
  10. Mar 6, 2016 #9

    davenn

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    that's true, because (say on a calm, no wind day) there would still be significant wind resistance against you and would cause you to land behind the point you jumped from

    adding a wind from any direction will vary the results

    Dave
     
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