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B Definition of work

  1. Apr 22, 2016 #1
    Can work be explained in following context-

    Work done is the amount of energy exchanged in executing an action through non-spontaneous method.
  2. jcsd
  3. Apr 23, 2016 #2


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    What does this mean?
  4. Apr 23, 2016 #3


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    This is good. The rest seems wrong. The usual definition is "energy exchanged by any means other than heat"
  5. Apr 23, 2016 #4
    I think the equation W=Fd explains it all. If a force acts on a body, it gives it energy, potential or kinetic, or it does work to the system.
  6. Apr 23, 2016 #5
    Just to add, say you cover up a positively charged magnet with a thick material so that it can't affect a nearby negatively charged particle. For one millisecond, you uncover the magnet and the particle quickly accelerates towards the magnet. This is spontaneous, is it not? Was work done? Yes.
  7. Apr 23, 2016 #6


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    It's probably better to say "acts for a distance" instead of "acts on a body" (put a weight on a table and a force is acting on the table but no work is being done - unless the table breaks under the load)... But with said, yes W=Fd does pretty much say it all.
  8. Apr 23, 2016 #7


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    I think that it should be made clearer that this is the definition of work done 'on' an object and not the work done 'by' an agency. This would remove the possible confusion when efficiency is brought in. The 'agency' could be doing much more work than is being usefully provided to the object.
  9. Apr 23, 2016 #8


    Staff: Mentor

    I prefer the "energy transferred" definition because it applies for fields too, and it helps me keep things straight in complicated scenarios.
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