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Homework Help: Calculating Work done by a force

  1. Apr 26, 2010 #1
    [/COLOR]1. The problem statement, all variables and given/known data
    [URL]http://einstein.math.fsu.edu:9080/testbanks/wiley/math/1114ptF08/cch/images/qu.215.9.question.gif[/URL]

    2. Relevant equations
    I know that
    W = Fd where here it is
    W = F * [tex]{\rightarrow}{\}[/tex]AB

    Also, that

    (im sorry, this looks really ugly)
    [tex]\stackrel{v\rightarrow}{}[/tex] = ||v||(cos[tex]\alpha[/tex][tex]\stackrel{i\rightarrow}{}[/tex]+sin[tex]\alpha[/tex][tex]\stackrel{j\rightarrow}{}[/tex])
    ||v|| = sqrt(a2+b2)


    3. The attempt at a solution
    I get stuck fairly quickly on this problem, my professor never went on it in class.

    using the second equation, I get to the point of

    v = (sqrt13)(cos+sin)

    I am not sure what goes into the cos and sin portion of the problem, I am assuming it has something to do with the coordinates it gives, but other than that, I have no idea.
     
    Last edited by a moderator: Apr 25, 2017
  2. jcsd
  3. Apr 26, 2010 #2

    rock.freak667

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    Homework Helper

    Ok, so your force is 5lbs in the direction of 3i+2j, so what is your force vector F?

    The displacement is from (0,0) to (0,4), what is you displacement vector d equal to?
     
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