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Homework Help: Atwood Machine and the Work done

  1. Aug 17, 2010 #1
    The two block in an atwood machine have masses 2kg and 3kg. Find the work done by gravity during the fourth second after the system is released from rest.


    I have attached my attempt here..Kindly tell me where I went wrong.
    I am sure that I didnt go anywhere wrong in finding the acceleration and the displacement. But, I am doubtful abt the work done part. The answer is coming out to be 67 joules. :confused:
     

    Attached Files:

  2. jcsd
  3. Aug 17, 2010 #2

    Doc Al

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    Staff: Mentor

    What's the displacement during the fourth second? (That's from t1 = 3 s to t2 = 4 s.)

    Also realize that one mass moves up while the other moves down, so the work done on each will have a different sign. Presumably, you want the net work done?
     
    Last edited: Aug 17, 2010
  4. Aug 17, 2010 #3
    ooooh!!! I am so sorry...! THat's a silly mistake..! :P
     
  5. Aug 17, 2010 #4

    Doc Al

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    Staff: Mentor

    See also the comment I added to my last post.
     
  6. Aug 17, 2010 #5
    THanks a lot! I understood the concept.... :)
     
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