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Homework Help: Linear and Rotational Motion Question (really struggling)

  1. Apr 28, 2010 #1
    Linear and Rotational Motion


    A load of mass 60kg is hoisted vertically by means of a light rope running over a pulley and is accelerated from 3 to 6m/s while traveling through a distance of 6 meter. If the resistance due to friction is 50N determine

    A) The pulling force in the rope
    B) The work done
    C) Average power required to accelerate this load



    So far all i have is
    F=Mg-Ma=M(g-a)
    Do i need to include my 50N friction resistance?

    i have F=60(9.81-6)= 228.6N

    For my work done i have
    Work done=ForcexDistance?

    Which i work out to be W.D.=(228.6+50)x6=1671.6W

    For average power i have
    Average power=W/t
    and intera torque =Ia
    However i dont know whaere to substitute in the values

    Im really stuuggling with this question and its importan for me to get correct if i want to progress onto the next course. Any hints will be much appreciated.
    Thankyou
     
  2. jcsd
  3. Apr 28, 2010 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF

    Hi Dan_fitz91HNC! Welcome to PF :smile:
    (where did the 6 come from? :confused:)

    Sorry, but you need to be more systematic. :redface:

    First, find the acceleration, using one of the standard constant acceleration formulas.

    Then you can use F = ma (and yes, you have to include all the forces in F). :wink:

    What do you get? :smile:
     
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