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Homework Help: The Work-Energy Theorem

  1. Mar 14, 2006 #1
    Hello,

    If the work changes the object's velocity through a horizontal distance then:

    W = delta KE

    But, what if the work changes the object's vertical position. Then the object's mph changes. Would the Work formula be:

    W = delta PE?

    But, if something is moving upwards (y axis) then it has both a change in PE and KE. What would the new equation be for total work? I'm confused because we are only taught the W = delta KE equation.

    Thank you. :-):approve:
     
  2. jcsd
  3. Mar 14, 2006 #2

    Well, later in your textbook, or class, you will learn something call the conservation of mechincal( spell?) energy. which is:

    W= delta E

    where delta E is the sum of both delta PE , and delta KE plus.... others(but you don t need to know yet)

    Since you know PE, then i assume you also know that work done by a conservative force is path independent. Using the same generialization, you can compute delta E once you know the initial , and final state of the thing you called: system.
     
    Last edited: Mar 14, 2006
  4. Mar 14, 2006 #3
    It's generally more helpful to ignore seperate formulas and just remember that w = deltaME where ME is mechanical energy, and is, as kant said, the sum of kinetic and potential energy of an object in a system.
     
  5. Mar 15, 2006 #4
    this formula w = deltaME I will for sure write down

    thank you all for your help :-)
     
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