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Bullet fired from a gun

  1. Dec 3, 2015 #1
    If a bullet is fired from a gun perfectly parallel to the ground and a bullet is dropped from that same height at the same time which one hits the ground first?

    Sorry for the two late edits. 1. The gun is not dropped, the gun is locked in a vice and perfectly level to the ground. 2. The bullet in your hand is released at the end of the gun barrel and just dropped.
     
    Last edited: Dec 3, 2015
  2. jcsd
  3. Dec 3, 2015 #2

    PeroK

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    I guess it depends which way the gun is pointing. If you fire at the ground that bullet will get there first.
     
  4. Dec 3, 2015 #3
    If the bullet is fired perfectly horizontally, the gun is dropped at the exact same time, and if wind resistance is neglected (i.e. doing this in a vacuum), then they will both hit the ground at the same time.

    (well, neglecting the shape of the gun--in a real gun, the handle would hit the ground first, but the bullet comes out of the barrel, so it has a longer distance from the ground)
     
  5. Dec 3, 2015 #4

    mathman

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    Previous posts seem to have misunderstood the question. In a vacuum both bullets would hit the ground at the same time.

    When air resistance is taken into account it depends on the orientation of the dropped bullet, as well as other factors. I wouldn't try to guess the net result.
     
  6. Dec 3, 2015 #5

    PeroK

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    Who needs PF when you've got YT:

     
  7. Dec 4, 2015 #6

    A.T.

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    Earth's curvature and rotation make it even more complicated. But for short ranges this can be neglected.
     
  8. Dec 4, 2015 #7
    The direction in which you require the time is vertical. Initial velocities of both the particles in the vertical direction is same that is 0.Equal amount of acceleration acts in the vertical direction that is g. No other forces act on the vertical direction. Using 2nd equation of motion in the vertical direction, s=1/2gt2 (as u=0),t comes out to be equal as s and g are same in both the cases.
     
  9. Dec 4, 2015 #8

    sophiecentaur

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    The difference in arrival time can easily (?*)be explained in terms of the actual launch angle of the fired bullet. A degree up or down would represent a significant difference in drop time for the fired bullet. I wasn't clear as to how they got their launch elevation to be zero - in the end, the best method would probably to do the experiment the other way round and use the synchronous landing to get the launch horizontal.
    *The sums are easy for someone with time to spare.
     
  10. Dec 4, 2015 #9
    Due to the non-linear air resistance the dropped bullet should hit the ground first.
     
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