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Homework Help: Calculating minimum force

  1. Sep 17, 2009 #1
    1. A 1 tonne rock is being dragged up a 30 degree slope using the a pulley system.
    If there is a constant resistance to movement between the rock and the ground of 350N, calculate the minimum force necessary to drag the rock up the slope.


    3. All i got so far is

    1t = 1000kg

    1000kg x 9.8 (gravity)
    Acting upon the slope from the rock
  2. jcsd
  3. Sep 17, 2009 #2
    Set up a free body diagram to find the forces acting on the rock.

  4. Sep 17, 2009 #3


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    Science Advisor
    Homework Helper

    Hi vbillej! :smile:
    No, that's wrong …

    9800N is the force of gravity on the rock.

    There are four forces on the rock … gravity, normal force, friction force (= 350N), and the force from the rope.

    As CFDFEAGURU :smile: says, set up a free body diagram.
  5. Sep 18, 2009 #4
    Thanks both of you for your replies

    Yes i forgot its actually the weight from the rock, thanks for reminding me
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