1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Yet another static equilibrium problem.

  1. Sep 22, 2008 #1
    The figure shows a wheel on a slope with inclination angle 16 degrees, where the coefficient of friction is adequate to prevent the wheel from slipping; however, it might still roll. The wheel is a uniform disk of mass 1.35 kg, and it is weighted at one point on the rim with an additional 0.960 kg mass. Find the angle PHI shown in the figure such that the wheel will be in static equilibrium.

    [​IMG]
    [​IMG]

    I understand this:
    m sin(phi) R = M sin(theta) R

    However, this does not give me the right answer. So how do I solve this?
     
  2. jcsd
  3. Sep 22, 2008 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Hi akan! :smile:

    Hint: you don't want the wheel to turn

    so take moments about a suitable point (to find the torques of the forces), and put that equal to zero. :smile:
     
  4. Sep 22, 2008 #3
    What would be a suitable pivot point here? Thanks.
     
  5. Sep 23, 2008 #4

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    moments of forces

    oh come on! :rolleyes:

    I can only see two possible pivot points …

    choose one of them, and see if it works! :smile:
     
  6. Sep 23, 2008 #5
    Sorry, I suck with pivot points. If I put it at the center, then gravity is acting parallel to the level arm, so that ain't gonna work. If I put it at the circumference, then the whole thing is just going to be weird. So where do I place it?
     
  7. Sep 24, 2008 #6

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Place it at the point of contact (between the wheel and the slope).

    There, the torque of the reaction and friction forces will be zero (that's why you're choosing it :wink:), so you just have m and M to balance … like a see-saw! :smile:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Yet another static equilibrium problem.
Loading...