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!

Spinning Object on Flat Surface

  1. Nov 3, 2007 #1
    I'm working on a computer simulation, but I'm not sure how to approach this problem. I want to find the change in angular velocity on an object rotating on top of a flat plane.

    So far this is what I have:
    (* == multiplication not dot product)

    Ff x r = I * alpha
    Ff x r = I * dv/dt

    I can find I, Ff, and dt. I assume Ff x r can be reduced to Ff * r because the friction will always be perpendicular. I don't know what r is though, because the object is flat aren't there a ton of different particles experiencing the Ff? I'm I going to have to integrate all the little Ff x r? I'm pretty lost. Any direction would be wonderful.
  2. jcsd
  3. Nov 4, 2007 #2

    Chi Meson

    User Avatar
    Science Advisor
    Homework Helper

    Instead of Ff x r, just use frictional torque, which is what Ff x r is. How would you measure Ff anyway?
  4. Nov 15, 2007 #3
    Thank you very much for your reply.
    I think Ff is what is confusing me. I know the friction coeffecient, and I know how to find the normal. How can I find the friction torque? If ForceOfFriction = NormalForce * FrictionCoeffecient, what does the FrictionTorque = ?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook