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 Momentum of a conical pendulum

  1. Jul 14, 2007 #1
    1. The problem statement, all variables and given/known data

    A small metallic bob is suspended from the ceiling by a thread of negligible mass. The ball is then set in motion in a horizontal circle so that the thread describes a cone.
    Given: Length of string = 2.8m
    Angle between string and vertical: 21 degrees
    Mass of bob: 2.9kg

    2. Relevant equations

    I = mr^2
    w = square root of [g/(lcos(theta)]
    Momentum = I x w

    3. The attempt at a solution

    I first calculated the angular velocity by plugging numerical values into the equation and got 1.936 rad/s. Then, I found out the moment of inertia of the bob by multiplying 2.9 x 2.8^2 [this is the step I'm not sure of], but the answer wasn't right. Is there something I missed out?
    Thank you for your help!
  2. jcsd
  3. Jul 14, 2007 #2
    The raidus is wrong. It should be r * theta
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?