1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Rigid body dynamics: falling stick

  1. Apr 7, 2015 #1
    1. The problem statement, all variables and given/known data
    A stick of length L and mass m is falling on a table with kinetic friction uK and static friction uS. Find the equation that determines whether the rod will stick or slip.

    If m = 10kg and L = 100cm, uS = 0.8, uK = 0.7 and initial theta = 30 degrees find the initial accel for stick and slip.
    2. Relevant equations
    Irod = (1/3)mL^2
    M= r x F

    3. The attempt at a solution
    I'm so stuck.

    I made an FBD but as far as I can see, there are no forces in the X-direction, so what exactly makes the thing slip?
    Last edited: Apr 7, 2015
  2. jcsd
  3. Apr 7, 2015 #2
    From my FBD:

    Iα = -mg(L/2)Sinθ

    then α = -(3/2L)gsinθ

    so far so good?
  4. Apr 7, 2015 #3
    By which the translational x-acceleration of the rod must be (taking positive x to the left):

    Ax= -αRSinθ - uK*N / m

  5. Apr 8, 2015 #4
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted