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Another Problem Involving Cars lol k.

  1. Jan 22, 2006 #1
    Sorry I am asking a lot of questions. =\. lol k. : ].

    [​IMG]

    Here's what I tried to do.

    Fx= 450 cos 80 + 400 cos 60
    = 278 N
    Fy= 450 sin 80 + 400 cos 60
    = 789 N

    278^2 + 789^2
    =622521
    = 836.5


    which is not the answer in the back of the book. Can someone help me out please? lol k. : ]. lol k. : ].
     
  2. jcsd
  3. Jan 22, 2006 #2

    Pyrrhus

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    You seem to not have or ignore a sign convention. The standard is up and right is positive. Also unless your axis are rotated by 90 degrees, your Fx and Fy are misplaced. Look at the triangles.

    [tex] 450 \vec{\lambda} = - 450 \sin 10^{o} \vec{i} + 450 \cos 10^{o} \vec{j} [/tex]

    [tex] 400 \vec{\lambda} = 400 \sin 30^{o} \vec{i} + 400 \cos 30^{o} \vec{j} [/tex]
     
  4. Jan 22, 2006 #3
    The answer in the back is 789 N... : [. How did it arrive to that answer with an angle of 8.8 to the foward direction. : [.
     
    Last edited: Jan 22, 2006
  5. Jan 22, 2006 #4
    The answer in the back is 789 N... : [. How did it arrive to that answer with an angle of 8.8 to the foward direction. : [.
     
  6. Jan 22, 2006 #5

    Pyrrhus

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    didn't you understand my reply?
     
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