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Work Energy Theorem and total work

  1. Jan 4, 2013 #1
    Plz tell me
    Which is correct form of Work Energy theorem
    1. Total Work = Toatl change in Mechanical Energy(Potental + Kinetic)
    2. Total Work + Potential Energy = Total Change in Kinetic Energy
    3. Total Work = Total Change in Kinetic Energy (Mention in the text books)

    Actually i am confused when i prove Bernoulli Theorem for fluid.
    Some writers use Total Work done(Due to pressure) + Change in Potential Energy = Change in Kinetic Energy

    I think the expression is this one

    Total Work done(Due to pressure) = Total Change in Mechanical Energy(Potential Energy + Kinetic Energy)
  2. jcsd
  3. Jan 4, 2013 #2


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    2017 Award

    Staff: Mentor

    It depends on the signs you use.
    Total energy is conserved.
  4. Feb 18, 2013 #3
    If mechanical energy is conserved , then you have : T1+ V1 = T2+V2
    (T: kinetic energy, V: potential energy)
    It can be written as T2-T1=V1-V2=>DT=-DV
    Thus the potential energy diminishes. The amount of change in the potential energy is the work done, which is finally converted in kinetic energy, thus increasing its value.
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