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Discuss physics at the General Archery Discussion & News within Archery Interchange Forums; TJ Mason got it right. Here's my variation on shooting backwards from the car: (1) ...
  1. #55
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    TJ Mason got it right. Here's my variation on shooting backwards from the car:

    (1) Imagine the vehicle is in outer space, no wind, no landscape, i.e. no points of reference:
    Arrow now leaves the bow at 90mph relative to the bow (& archer). If there's no gravity & no wind, it keeps on moving away from the archer at 90mph for ever.

    (2) Now add landscape, stationary observer, gravity, but still NO wind (not just yet!):
    The vehicle (car + archer + bow + arrow) is traveling past the observer from (e.g.) left to right. Arrow is shot right to left just as the car passes. Observer sees arrow standing still, then falling due to gravity until it lands at the observer's feet.

    (3) Now add in the effect of the wind:
    The (stationary) observer feels no wind 'cos it's a nice, calm day. The archer feels 90mph wind from behind. Before release, the arrow feels wind from behind, but then nothing following the release.
    Now, relative to the observer and the arrow, there is no wind resistance so the situation is very similar to (2) above. As a side effect, the arrow would wobble as it fell since there's no drag on the feathers.

    Note that Einstein would also claim that, relative to the archer:
    - the arrow gets shorter
    - the arrow gets heavier (more massive)
    - the arrow doesn't quite reach 90mph
    - the fletchings become more blue-ish
    - the observer would disagree on all these points.
    - BUT archer and observer would both be correct.

    --o-0-o--
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  3. #56
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    If the arrow was dropped off the side of the train travelling at 90mph, I doubt that the 90mph wind effect, would totally counteract the fact that it was travelling at 90mph relative to the ground. If it was released at arm's length away from the train, at the point of release it would be in almost still air. It would be travelling through still air at 90mph just as any arrow shot in still air at that speed.
    If the arrow is shot backwards from the train, at release the arrow is doing zero mph relative to the ground. If the wind around the train affects it, I doubt that it would give it a 90mph boost. After all, the wind effect disappears soon, if the release is made a reasonable distance from the turbulence.
    Under normal circumstances, arrows are shot uphill, so I guess the arrow would lift a little before gravity starts to overcome that and bring it down to the ground. The archer would see that rise and fall and see the arrow travelling into the distance at almost 90mph. perhaps a little disturbed in the initial flight and almost normal after that.

  4. #57
    Soaring I've taken part in an AIUK American Shoot.The Fonz Award.AIUK subscriber. TJ Mason's Avatar
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    Quote Originally Posted by Vagabond View Post
    TJ Mason got it right...
    12 years on, I'm not so sure I did. I now think the arrow would have a net velocity of zero. And it's a silver Clio these days.
    "People demand freedom of speech as a compensation for the freedom of thought which they seldom use." - Soren Kierkegaard
    Club: Phoenix Bowmen, Halifax, County: Yorkshire

  5. #58
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    Well, nobody spotted my deliberate (?) mistake:

    "- the fletchings become more blue-ish"

    Obviously, the archer would have experienced red-shift since it was moving away from him.
    ho-hum!

    V
    Not all who wander are lost.

  6. #59
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    I could say that I spotted that but was too polite to mention it; or I could say that I was making a gadget to simulate the situation and it has taken a while to complete. (Just finished actually; but too late.) Or I could tell the truth. heehee.

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