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Homework Help: Forces on an object, Force vector

  1. Sep 16, 2008 #1
    There are two forces on the 1.1 kg box in the overhead view of Fig. 5-37 but only one is shown. The figure also shows the acceleration of the box.

    IMAGE : http://www.webassign.net/hrw/05_37.gif

    (a) Find the second force in unit-vector notation.
    N i + N j

    (b) Find the second force as a magnitude and direction.
    N,
    ° (counterclockwise from the +x-axis is positive)

    I'm not exactly sure where to start. Using F=ma then F= (1.1)(12)=13.2
    so is the net Force 13.2
    and for N in part be would the answer be either 20tan(30) or 20/tan(30) ??
     
  2. jcsd
  3. Sep 17, 2008 #2
    You are asked to find the second force and not the net force.
    As you have calculated the net force and you know its direction, resolve it into components
    F(net)= -13.2 sin 30 i + -13.2 cos 30 j
    F1= 20 i
    F1+F2=F(net)

    Find F2 now
     
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