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A 165N sled is pulled a distance of 205m. What angle?

  1. Nov 19, 2016 #1
    1. The problem statement, all variables and given/known data
    A 165N sled is pulled a distance of 205m. The task requires 5200J of work to overcome friction and is done by pulling a rope at what angle? Coefficient of friction is 0.25.

    2. Relevant equations
    W= Fdcos@ (@ for theta)
    F= ma

    3. The attempt at a solution
    My free body diagram had Force applied in the y direction (Fay) and normal force along the positive y axis and weight on the negative y axis. Force applied in the x direcrion (Fax) is on the positive x axis and the force of friction is on the negative y axis.

    I tried to solve for a variety of variables, but i can't get the right combination so two unknowns aren't in the same equation. I believe I need to find the force applied before I can get theta.

    I solved that Ff = Facos@ (Force applied in the x direction)

    For the y direction:
    Fasin@ = -N + W
    I solved for Fa then..
    Fa= (-N+W)/sin@

    I plugged that back into Ff= Facos@
    Ff= cos@* (-N+W)/sin@

    However, normal force is another unknown. I'm not sure where else to go from here.

    Thanks in advance.
     
  2. jcsd
  3. Nov 19, 2016 #2
    I think you meant "force of friction is on the negative x axis", true?


    Where does the 5200 J and 205 meter distance and 0.25 coeff. of friction come into play . . . or not?
     
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