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Homework Help: The Ballistic Pendulum

  1. Oct 16, 2013 #1
    1. The problem statement, all variables and given/known data
    Using trigonometry and Fig. 2 in the ballistic pendulum write-up, show that the height h the pendulum rises after capturing the ball is given by: h=R(1-cosθ)

    Figure two is here: http://imgur.com/W9nvVZT

    2. Relevant equations


    3. The attempt at a solution
    So in order for the height to increase I understand that R is the length of the pendulum. θ is the maximum deflection, so since R can't be negative that means cos(θ) must return a negative answer in order for the height to increase. So how do I prove that cos(θ) in this instance will be a negative number, thus making the height increase.
  2. jcsd
  3. Oct 16, 2013 #2
    I'm an idiot and figured this question out the second I hit submit, so nevermind I got it! Not sure how to delete a post or if I just let it go!
  4. Oct 16, 2013 #3


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    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    If you had been an idiot, you wouldn't have found it out by yourself, nor would the best teacher in the world (not me!) been able to make you understand.
    So, conclusion:
    You are not an idiot after all! :smile:
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