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Forces and rotational motion

  1. Nov 19, 2013 #1
    1. The problem statement, all variables and given/known data

    This question is about forces and rotational motion.
    (a) Figure 1.1 illustrates a force of 180 N acting at a perpendicular distance of 0.40 m from a point O. Calculate the torque about O.

    (b) Figure 1.2 illustrates a circular drum of radius 0.080 m around which a rope is wound. The drum is turned by means of a handle of length 0.40 m to which a force of 180 N is applied at right angles to the handle.
    Calculate the tension T in the rope.

    (c) A person is pulling a boat on to a trailer using the drum system from (b), known as a winch, as shown in Figure 1.3. The person is exerting a force of 180 N on the handle.
    Calculate the force which the trailer exerts on the axle of the winch when the handle is in the position shown in Figure 1.3.

    2. Relevant equation

    3. The attempt at a solution

    (a) Torque=Fr=180(0.4)=72Nm
    (b) ƩT=0
    T=180(0.4)/0.08=900 Nm

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  2. jcsd
  3. Nov 19, 2013 #2


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    Your a) and b) answers are right. What's your thinking on c)?
  4. Nov 19, 2013 #3
    i am trying to figure out the free body diagram for part c
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