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: Cylinder Question

  1. Oct 25, 2007 #1
    1. The problem statement, all variables and given/known data


    M, a solid cylinder (M=1.67 kg, R=0.137 m) pivots on a thin, fixed, frictionless bearing. A string wrapped around the cylinder pulls downward with a force F which equals the weight of a 0.670 kg mass, i.e., F = 6.573 N. Calculate the angular acceleration of the cylinder.


    2. Relevant equations

    F*R ?
    ang accel. = alpha*R

    3. The attempt at a solution

    I multiplied Force*Radius, cause someone told me to start with that, but I'm not sure what to do next? Do I have to use a=9.81 m/s^2? I'm not really good at this stuff so if someone could help me that would be great!! thanks!
     
  2. jcsd
  3. Oct 25, 2007 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    You already did use a=9.81m/s^2 when you found the weight of the hanging mass.
     
  4. Oct 25, 2007 #3
    so should I still do Force * radius...then what?
     
  5. Oct 25, 2007 #4

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Force*radius is torque. Then you need to find moment of inertia. Then T=I*omega. Just like F=ma, right?
     
  6. Oct 25, 2007 #5

    dynamicsolo

    User Avatar
    Homework Helper

    I think you want I ยท alpha there , since alpha is angular acceleration.
     
  7. Oct 25, 2007 #6

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Oh, yeah. I had a funny feeling while I was writing it. Guess I'm forgetting what greek letters look like written in english. Thanks.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook