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Ballistic Pendulum calculation

  1. Dec 6, 2008 #1
    1. The problem statement, all variables and given/known data
    So does anyone here know a lot about ballistic pendulums? I was just wondering how I could calculate the distance the ball will travel horizontally when shot horizontally, from a table.

    2. Relevant equations

    3. The attempt at a solution
    I know that first, I have to calculate the velocity of the ballistic pendulum, v=(m+M)/m* sqrt(2gh). Now, my problem is, how can I measure precisely enough to predict exactly where the ball will land? Like, specifically, what is "h" ? And from this initial velocity, how do I calculate the distance using kinematics? thanks!
  2. jcsd
  3. Dec 6, 2008 #2
    I don't know what that formula is. And if you don't either, I would not suggest using it.

    Instead, I would ask myself what principles could I apply to this problem.

    What principles do you know of that apply to collisions.
  4. Dec 6, 2008 #3


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    Homework Helper

    I'd suggest that you watch the first part of this lecture:
    http://ocw.mit.edu/OcwWeb/Physics/8-01Physics-IFall1999/VideoLectures/detail/embed17.htm [Broken]

    It covers pretty much what you want to know.
    Last edited by a moderator: May 3, 2017
  5. Dec 6, 2008 #4
    Oh ok, thanks that website video really helped me, but one last problem: it did not talk about how far the bullet would travel if it were shot horizontally. Like, if it were shot off the table, how far away would it land horizontally? Would I use kinematics? If so, how? I would have the initial velocity, final velocity (0), but how bout acceleration and time? thanks
  6. Dec 6, 2008 #5

    Doc Al

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    Staff: Mentor

    So this is a different question than the one about a ballistic pendulum, right? Your initial post is not clear as to what you are trying to do.

    If you shoot a bullet horizontally, its initial vertical speed will be zero. Figure out how long it takes to fall to the ground. (Its final speed as it hits the ground will not be zero.) This is a projectile motion problem: treat the vertical and horizontal motions separately.
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