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Solving for Work

  1. Oct 1, 2016 #1
    1. The problem statement, all variables and given/known data
    On a farm, you are pushing on a stubborn pig with a constant horizontal force with magnitude 34.1 N and direction 37.0∘counterclockwise from the +x-axis.

    a) How much work does this force do during a displacement of the pig that is s⃗ =(5.00m)ι^?

    b) How much work does this force do during a displacement of the pig that is s⃗ =−(6.00m)j^?

    c) How much work does this force do during a displacement of the pig that is s⃗ =−(2.00m)ι^+(4.00m)j^?

    2. Relevant equations
    W = F*d

    3. The attempt at a solution

    I drew this out of the given problem but I'm not sure if it is right:
    boVBtZ2.jpg

    With that drawing I solved for
    Fx = Nsin37.1 = 34.1sin37.1 = 20.7N
    Fy = Ncos37.1 = 34.1cos37.1 = 27.2 N
    Fr = 34.2 N

    1.) At first i multiplied the resultant to 5m to get W but that didn't work. So I took the Fx = 20.7 and multiplied that to 5m but that didn't work either.

    What to do?
     
  2. jcsd
  3. Oct 1, 2016 #2

    SammyS

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    The problem states that the direction of the force is 37.0° counterclockwise from the positive x-axis.

    Your sketch shows a force that's 37.1° clockwise from the positive y-axis.

    That could cause an error .
     
  4. Oct 1, 2016 #3
    Okay so it should be looking like this? :
    gDGvZZ1.jpg
     
  5. Oct 1, 2016 #4

    kuruman

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    No. The positive x-axis is horizontal and points to the right. Start there and go counterclockwise 37.1o.
     
  6. Oct 1, 2016 #5

    haruspex

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    Further to kuruman's comment, please label the axes (+X, -X, +Y, -Y) to ensure no misunderstanding.
     
  7. Oct 1, 2016 #6

    SammyS

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    Is some of the difficulty here caused by the overwhelming use of digital clocks these days ?
     
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