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Need Clarification about Work

  1. Mar 12, 2015 #1
    (1) Wnet = ΔK
    (2) Wnc = ΔE

    1. Is equation (1) always correct even if the potential energy of the object is also changing? A
    2. Is equation (2) always going to have a small value than Wnet? And is Wnc always 0 if Wnet is zero?
     
  2. jcsd
  3. Mar 12, 2015 #2

    Doc Al

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    Staff: Mentor

    Yes, as long as you include the work done by ALL forces acting. This is the so-called "work-energy" theorem. (There are some subtleties, which I won't confuse you with.)

    No.

    No.

    Example: Imagine a block sliding down an incline at constant speed. (Friction is obviously acting.) The net work including all forces will be zero. But the work done by friction (the non-conservative force in this example) will not be zero.
     
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