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: Angular velocity-please help

  1. Mar 10, 2010 #1
    1. The problem statement, all variables and given/known data
    a small puck of mass .5kg is executing Uniform constant motion on a friction free horizontal table. The angular frequency of the puck is 10 sec-1 (counter clockwise) and the radius of the circular motion is .8m. the radius stays fixed as the student holds the string in place. he now pulls the string down .5 m and holds it again in place. what work did he do?

    2. Relevant equations

    KE(original)+ W = KE (final)
    inertia of hockey puck on string = mr2
    w = angular velocity
    I = inertia

    3. The attempt at a solution
    KE(original)+ W = KE (final)
    .5(I)w2 +W = KE final
    .5 (.5)(.8)2(102) + W = KE final

    now i have a problem solving for kinetic energy final...
    KE final = .5(.5)(.5)2(102)(w2)
    I cant figure out what w (angular velocity) is...
    please help!!!
  2. jcsd
  3. Mar 10, 2010 #2


    User Avatar
    Homework Helper

    Have you tried using the conservation of angular momentum?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook