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Homework Help: What am I supposed to include?

  1. Jun 12, 2012 #1
    Ok, so we've been set some pretty easy homework involving energy transfers e.g. Kinetic energy --> sound energy..

    And in 1 of these questions it involves 2 clock which require no electricity to function the first is a pendulum clock with a cord where you lift up a weight which will slowly fall powering the clock. So here's what I put:
    Kinetic energy--> Gravitational potential energy--> Kinetic energy.

    The second clock has a coil which is tightened and as it slowly unravels it powers the clock. So here what I put:

    Kinetic energy-->Elastic potential energy--> Kinetic energy.

    Now here's my problem in these basic G.C.S.E. Transfer questions should I include Sound energy? (for the clock ticking.)

    Would you of put the sane answers as me?
  2. jcsd
  3. Jun 12, 2012 #2
    For GCSE, I probably wouldn't consider sound energy, and just base it on mechanical energy conservation.

    But actually, there is heat generated due to friction, at the hinges, friction due to air resistance also causes heat. And of course, there is sound energy loss. It might even have a very very very tiny electric energy loss/gain due to 'rubbing' with air molecules, and getting/losing electrons.
  4. Jun 12, 2012 #3
    But for energy transfers do you include waste energy?
  5. Jun 12, 2012 #4
    As a general trend, assuming a friction free environment, and no air(no air=no tick-tock :wink:), basically, you cannot have any of the waste energy losses I listed. This is probably what your question asks for. Just pure KE and PE.
  6. Jun 12, 2012 #5
    Yeah thats what I initially thought but then had some doubts. Thanks though. :)
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