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Homework Help: Work on an object

  1. Jun 22, 2008 #1
    1. The problem statement, all variables and given/known data
    Object one pushes on object 2 as the objects move together, like a bulldozer pushing a stone. Assume object 1 does 15 J of work on object 2. Does Object 2 do work of object 1? If possible determine how much work?

    2. Relevant equations



    3. The attempt at a solution
    I was thinking it would do work on object 1, could someone just point me in the right direction on how to start this. I'm not real sure where to begin. I was thinking it might be negative work that the 2nd object does on number 1.?????
     
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  3. Jun 22, 2008 #2

    rock.freak667

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    What is needed for an object to do work?
     
  4. Jun 22, 2008 #3
    Force and distance moved?
     
  5. Jun 23, 2008 #4

    rock.freak667

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    What is the force that object 2 exerts on object 1?
     
  6. Jun 23, 2008 #5
    I am pretty sure that the answer is 15J.

    Lets try it with numbers (although they don't really matter.) Lets say the bulldozer applies 5 Newtons for 3 Meters (3*5=15). This means that if the rock was not present, it would take 15 Joules less to move those 3 Meters. You can think of this -15J as the work that the boulder does on the bulldoser. It is the extra energy that the bulldozer has to do for those 3 meters (or any distance for what it matters).
     
  7. Jun 23, 2008 #6

    rock.freak667

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    Basically it was just to apply Newton's third law.
     
  8. Jun 23, 2008 #7
    Thanks a bunch!!!
     
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