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A Curious question About Ballistic Pendulum Solution

  1. Jan 18, 2015 #1
    I've watched a video about ballistic pendulum problems.
    The illustration is :
    5l9e28.jpg

    I wonder why the final energy is just a gravity potential energy.
    I think there is also a rotational kinetic energy (since it will rotate and oscillate)
    Is my thought wrong?
     
  2. jcsd
  3. Jan 18, 2015 #2

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    What's the rotational velocity at the "peak" of the pendulum displacement?
     
  4. Jan 18, 2015 #3
    I'm not quite sure. But, I think it will be v/r
    Am I right ?
     
  5. Jan 18, 2015 #4

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    In your sketch, where the maximum displacement from the vertical is indicated to be sixty degrees, how fast is the pendulum moving?
     
  6. Jan 18, 2015 #5
    Do you mean the velocity ?
    I think it's 0 m/s since it has reached the amplitude.
    Oh yeah.. Thank you for your answer.
    I get it now.. Because the velocity is zero, so the rotational kinetic energy is zero !
     
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