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!

Angular velocity question

  1. Sep 17, 2006 #1
    A solid uniform disk of mass m and radius R is pivoted about a horizontal axis through its center, and a small body of mass m is attached to the rim of the disk. If the disk is released from rest with the small body at the end of a horizontal radius, find the angular velocity when the body is at the bottom.
    Loss of P.E., = gain in K.E. Therefore

    m*g*R = .5*I*w^2 + .5*m*v^2.

    Where I = rotational inertia and w = angular velocity.

    w=2*(g*R - 2*v)/R^2)^2.
    Is this correct, if it isn't why or where? Thanks very much.
  2. jcsd
  3. Sep 17, 2006 #2
    Note: I= .5*m*R^2
  4. Sep 19, 2006 #3
    I was woundering what is your ideas on above. Many thanks.
  5. Sep 19, 2006 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Since the disk and the small mass constitute a single object that ends up rotating at some angular speed, you need to find the rotational inertia of that composite object. The final KE will be .5*I*w^2, where I is the total rotational inertia.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Angular velocity question