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Quick Thinking Question

  1. Sep 24, 2012 #1
    You are playing darts in an elevator that is rising at a constant speed. Should you still aim at your target the way you would normally do, or should you aim higher, or lower? Explain.
     
  2. jcsd
  3. Sep 24, 2012 #2

    jtbell

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    What do you think?
     
  4. Sep 24, 2012 #3

    HallsofIvy

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    Remember that speed is "relative". (No "einsteinean relativity" required here, just "Gallilean relativity".)
     
  5. Sep 24, 2012 #4
    I feel like it would be the same because everything in the elevator is moving up at the same upward velocity, but I am not sure.
     
  6. Sep 24, 2012 #5
    Ah you are right. But in the period of time during which the dart is in the air, is the dart being pulled up like the rest of the elevator?
     
  7. Sep 24, 2012 #6
    Note that the problem states the elevator is rising a constant speed, and hence is not accelerating.
     
  8. Sep 24, 2012 #7
    Doesn't what I'm saying still matter though? If it is rising at a constant speed it means there is an acceleration equal to 9.8 m/s^2 up. The dart, in midair, doesn't feel this acceleration.
     
  9. Sep 24, 2012 #8
    Doh, yes you're definitely right. I thought you were implying there were pseudo-forces present in the elevator.
     
  10. Sep 24, 2012 #9
    Not true. If it is rising at a constant velocity, there is 0 acceleration up or else it would not be rising at a constant velocity.
     
  11. Sep 24, 2012 #10

    Drakkith

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    No, there is no acceleration if the velocity is constant.
     
  12. Sep 24, 2012 #11
    Of course, but the second the 'dart' leaves the thrower's hand, it's no longer being pushed up by the force of the rising elevator cart (mediated by your hand) and therefore it feels a downward force equal to g, right?
     
  13. Sep 24, 2012 #12

    Drakkith

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    It already feels a force downward equal to g before the throw. (Just like a dart supported by someone on the ground) Once it is released it is rising at the same velocity as the rest of the elevator and will act identically to a dart thrown on the ground.
     
  14. Sep 24, 2012 #13
    No, different acceleration is experienced due to altitude

    but the probability could be the same
     
    Last edited: Sep 24, 2012
  15. Sep 24, 2012 #14

    I see what I was thinking wrong. In my head I was thinking that the added velocity would make it seem like there was a greater acceleration, I can see why that is wrong.

    Thank you, and to the OP: listen to Drakkith.
     
  16. Sep 24, 2012 #15

    davenn

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    NO, :)

    read the several previous comments, The speed is constant, there is NO acceleration :)

    Dave
     
  17. Sep 24, 2012 #16
    Doing that on top of the high mountain is the same.. no acceleration but different g "acceleration due to gravity due to altitude" (should have use that phrase in my last post).
    Thus, lighter "darts" to throw . Aiming is a matter of memorizing the motor complex for certain dart flight..try 3 throws first probably the 4th is more precise.
     
    Last edited: Sep 25, 2012
  18. Sep 25, 2012 #17
    The dart would start to accelerate downwards due to gravity once it leaves your hand, but that happens when you are at ground level as well so you shouldn't have to adjust your aim.
     
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