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Homework Help: Need wording clarified

  1. Sep 13, 2010 #1
    1. The problem statement, all variables and given/known data

    3 forces act on a particle, it is in equilibrium, I am told about two of the three, asked to find the third.

    We have a certain force A and it is in the y-z plane, described by a certain angle Beta. Then I'm told that there is a second force B in the x-z plane, described by integer lengths of a similar right triangle. What does that mean?

    I have 2 attempts left on this question so I want to be sure. I am assuming it means it is described by the angle Beta in the x-z plane, but this isn't correct according to the website. What other interpretations could there be?


    I'll give you the numbers and my answer using the above: Beta is 31* A = 15.5 and B = 20.5
    Magnitude of C, the third equalizing force?

    Well sin31(A)+cos31(B) is the magnitude of the z component of the equalizing force. sin31(B) is the magnitude of the x component and cos31(A) is the magnitude of the y component. Squaring, adding, square rooting these terms gives 30.67 to 3 sig figs = 30.7, which is "wrong."

    edit: I think I solved it by finding a diagram hidden under "hints" but can anyone confirm if the problem statement (as above) is ambiguous?
    Last edited: Sep 13, 2010
  2. jcsd
  3. Sep 13, 2010 #2


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    Razzor7: One guess might be, force B is at an angle beta, which you already tried. A second all-out guess for the italicized phrase might be that it means force B is at an angle (90 deg - beta), except that it sounds like it might want you to increment the similar triangle only to leg lengths that are integers, which would give only certain lengths for vector B (?). We might be somewhat at a loss without the diagrams.
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