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K.E. and P.E. in a Pendulum and Spring

  1. Jan 19, 2015 #1
    Can anyone explain the conversion of K.E and P.E during compression and expansion of spring and during the motion of pendulum ?
     
  2. jcsd
  3. Jan 19, 2015 #2

    CWatters

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    Start with the pendulum. Which bit don't you understand? Do you know what PE and KE are?
     
  4. Jan 19, 2015 #3
    Yes .. i know that. I just want you to explain the interconversion of K.E and P.E as pendulum moves to and fro ,
     
  5. Jan 19, 2015 #4

    russ_watters

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    We're not going to do that. We require our members to put more effort than that into their own learning.
     
  6. Jan 19, 2015 #5

    CWatters

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    At maximum deflection the bob has maximum Potential Energy. Call that PEmax.

    Using Basic trig. you can calculate the bob height and hence the PE at any angle of deflection. Lets call that PE(theta) where theta is the instantaneous angle of deflection.

    Then applying conservation of energy...

    PE(theta) + KE(theta) = PEmax
    or rearrange that to give
    KE(theta) = PEmax - PE(theta)

    Edit: Sorry russ_watters is right. That's why I haven't calculated PE(theta) for you.
     
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