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Homework Help: Energy dissipated by friction

  1. Mar 1, 2010 #1
    I need help figuring out the equation for E :

    Find the amount of energy E dissipated by friction by the time the block stops. Express your answer in terms of some or all the variables m, v, and h and any appropriate constants.
     
  2. jcsd
  3. Mar 1, 2010 #2

    PhanthomJay

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    You'll ned to furnish a sketch or more info, and an attempt at a solution, before we can help....
     
  4. Mar 2, 2010 #3
    Since the problem states "by the time the block stops." we can assume the final energy is purely potential energy.

    So one possibility could be finding the initial potential and kinetic energy and subtracting the final potential energy from those.

    KEi+PEi-PEf=Energy lost

    Then plug in your variables for KE and PE

    This is assuming energy is not being lost due to any force other than friction.
     
  5. Mar 2, 2010 #4

    PhanthomJay

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    Yes, looks very good! You even got the plus and minus signs correct :cool: Now just adapt that to your given problem.
     
  6. Mar 2, 2010 #5
    Thanks! This helped me alot :)
     
  7. Mar 2, 2010 #6

    PhanthomJay

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    OK, but just remember (because I forgot!) that total energy can neither be gained nor lost...it is always conserved. What energy is lost due to friction is compensated for by an increase in heat, sound, and other forms of energy.
     
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