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Homework Help: Determine the work as objects moves in straight line

  1. Mar 11, 2012 #1
    1. The problem statement, all variables and given/known data
    Assume that a force acting on an object is given by F=axi+byj, where a=2.9 N/m and b=3.9 N/m. Determine the work done on the object by this force as it moves in a straight line from the origin to r=(10.0i +21.5j)

    3. The attempt at a solution
    i used the given info to calculate the magnitude of the Force. F=2.9(10)+3.9(21.5)=112.9. i then calculated the distance traveled by doing arctan (21.5/10)=23.7. W=FΔx, W=112.9x23.7=2675. which is wrong, apparently the answer is roughly 1000 J.
  2. jcsd
  3. Mar 11, 2012 #2


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    Gold Member

    Maybe you should try calculating the work directly from the definition:

    W = ∫(0,0(10,21.5) (ax i + by j). (dx i + dy j)

    =∫010 ax dx + ∫021.5 by dy

    = (a/2) x2|010 + (b/2) y2|021,5

    Complete the evaluation and see how that works out for you.
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