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Elastic Potential Energy stored in rubber band

  1. Oct 7, 2007 #1
    Hello Everyone.

    It has a year since I have worked with Elastic Potential Energy & I have forgotten the formula to work it out.
    I have this question and would appreciate it if anyone could tell me how to do it, or tell me the formula of how to work it out.

    So here it is:

    Rachel pulls back a 0.002 kg rubber band and flicks it across a room with a speed of 10m/s.
    What was the elastic potential energy stored in the rubber band just before it was released?

    Im sure this is extreamly simple to most of you, but please help me out :)

    Thanks,
    Phykid
     
  2. jcsd
  3. Oct 7, 2007 #2

    Hootenanny

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  4. Oct 7, 2007 #3
    Thanks for the very fast reply, but that is a little to complex for me!
    I just need to know how to find the EPE using the mass & speed.

    Thanks again,
    Phykid
     
  5. Oct 7, 2007 #4

    Hootenanny

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    Yes you do, but can you work out the kinetic energy...?
     
  6. Oct 7, 2007 #5
    Yes, 0.1J if I have done it right.

    (Please excuse the newbie questions. I'm only 14 and not done this in a year)
     
  7. Oct 7, 2007 #6

    Hootenanny

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    Spot on, so where do you think that the elastic band got this kinetic energy from?
     
  8. Oct 7, 2007 #7
    The stretch? :)
     
  9. Oct 7, 2007 #8

    Hootenanny

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    Correct, so how much potential energy was stored in the band?
     
  10. Oct 7, 2007 #9
    0.1? :s
    You've just lost me
     
  11. Oct 7, 2007 #10

    Hootenanny

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    Correct! :smile:

    When you let go of the elastic band, it flew off somewhere with 0.1J of kinetic energy. That kinetic energy couldn't have just 'appeared' from somewhere; the energy was stored as potential energy in the elastic band as you were stretching it. When you let go of the elastic band, this potential energy was turned into kinetic.

    Does that make sense?
     
  12. Oct 7, 2007 #11
    Brilliant :D

    Thanks alot, for your help & patience :)
     
  13. Oct 7, 2007 #12

    Hootenanny

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    No problem :smile:
     
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