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Homework Help: Torque balance

  1. Apr 12, 2008 #1
    <a href="http://www.flickr.com/photos/just-karl/2407404197/" [Broken] title="IMG_8600 by Karl W., on Flickr"><img src="http://farm3.static.flickr.com/2206/2407404197_18ab7a3497.jpg" width="500" height="317" alt="IMG_8600" /></a>

    I have to find at what the angle of the string is using the torque balance equation.

    W= 167.4grams
    a= 49cm
    b= 98cm
    m= 100grams
    The angle is 51 degrees based on the measurements during the lab, but I have to figure out how to do it using the torque balance equation.

    What my guess is for the equation is Wga = mgbsin(angle

    Am I going in somewhat of the right direction? Also how would I get the angle by it's self. Or how do you move sin if I do at all?

    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Apr 12, 2008 #2
    sorry, I didn't put the diagram in right.

  4. Apr 12, 2008 #3
    yes, you are correct, now just solve for the angle. You need to use the inverse sinus function.
  5. Apr 12, 2008 #4
    When I punch it into my calculator I get error in the domain. It'd be sin^-1(Wa/mb correct?
  6. Apr 12, 2008 #5
    yes, and it works fine for me and i get 56 degrees. try again.
  7. Apr 12, 2008 #6
    if I calculate wa/mb then do sin_-1 it works out. Thanks

    I have another question with this same diagram. "What are the predicted values of P_x and P_y?" Would it just be zero for both of them since there is no torque on it?
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