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Energy Process.

  1. Nov 20, 2013 #1
    1.Keeping a spring compressed for 1 hour by fixing clip.
    2. Keeping the similar spring compressed for 1 hour by holding in our hands.

    What difference is there in the two processes?
    (Man gets tired means energy is spent. Does clip get tired? How?
     
  2. jcsd
  3. Nov 20, 2013 #2

    Simon Bridge

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    Welcome to PF.
    You have to think of these sortf of questions in terms of energy processes rather than using common-everyday terms. i.e. in the man, how does the energy get spent? What sort of energy?

    In terms of energy
    - what happens when someone puts a clip on a spring?
    - what happens in the human body when someone holds the spring closed?

    ... think your way through the entire process - you start with an uncompressed spring, compressing it stores energy in the spring: where did that energy come from?
    Does it use energy to keep the spring compressed to the same amount?
     
  4. Nov 20, 2013 #3
    This was my first question on the forum .I am really excited to have a quick response.Thank you very much Sir.I have still some doubts left related to this question.Will ask these soon.
    It seems a wonderful forum.
     
  5. Nov 20, 2013 #4

    russ_watters

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    Human muscles utilize chemical processes to generate forces even when not in motion. Static objects like springs and tables do not.
     
  6. Nov 20, 2013 #5

    sophiecentaur

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    I think it is more accurate to say that there is, in fact, movement within muscles. This is at a microscopic level as muscle fibres take over from one another. It still involves forces times distances which do not contribute to a Force times Distance on the thing you are supporting. Nothing more than a zero efficiency machine.
    You could imagine supporting a mass on a large number of rubber bands and constantly stretching some and relaxing others. The constant cycling process would involve energy loss (hysteresis) in each band but the net upward force could be arranged to be constant.
     
  7. Nov 20, 2013 #6

    Simon Bridge

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    Then, of course, you cannot hold your hands completely still ... for a variety of reasons.

    Russ and SophieCentaur are providing examples of what I was talking about.
    When we are saying is that when you hold something "still" with your body, you are using a dynamic process to do that, which averages out to that stillness.

    It probably needs to be worded in a way that is appropriate to your course though.
    Usually they want something about what sort of energy - kinetic vs potential - what sort of potential etc.
    You'll probably have examples involving biological processes in your course.
     
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