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Homework Help: Problem finding angular velocity

  1. Jan 17, 2008 #1
    [SOLVED] Problem finding angular velocity... !!

    1. The problem statement, all variables and given/known data

    The 9.65 lb uniform disk is pin supported at its center and is acted upon by a constant force of P = 1.45 lb as shown. The system starts from rest. Radius of disk is .470 ft

    The force P is going straight down from the disk and would spin the disk in a clockwise direction. The force P is at the end of a string.. making the disk spin.

    Determine the angular velocity after 4.45 seconds. (rad/s, +CCW)

    2. Relevant equations

    I know this problem involves a constant accel equation. I believe the right one is angvelfinal = angvelinitial + a*t

    3. The attempt at a solution

    The issue i have is that i can't figure out how to relate the force acting on the disk to turn it into acceleration. I have tried setting "Force*Radius=(.5*Mass*radius^2)angaccel" and solving for angaccel and then multiplying it by the time in order to get my angvel but i am having no luck. Any help i appreciated.
  2. jcsd
  3. Jan 17, 2008 #2
    any other info i need to give guys?? i have been on this question for two days lol. I can finish it i just can't figure out how i get from a force in lbs pulling down on a string turning a disc... to the acceleration of the disc. Ive looked through formulas and have had no luck anywhere.
  4. Jan 17, 2008 #3
    thanks guys, i figured it out. I was doing it right but somehow my numbers were off somewhere.
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