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: Dynamics rotating disk, solve for r and theta magnitudes

  1. Sep 15, 2010 #1
    1. The problem statement, all variables and given/known data
    A screen clipping of the problem is here: http://img529.imageshack.us/img529/1738/dynamicsquestion2.jpg [Broken]

    We have a circular disk that roates about its center, 0, with a constant angular velocity [tex]\omega[/tex] ([tex]\omega[/tex] = [tex]\dot{\theta}[/tex]. The disk carries two spring-loaded plungers. The distance b, that each plunger protrudes from the rim of the disk varies according to b = bo * sin (2[tex]\Pi[/tex]nt), where bo is the max protrusion (n is a constant of oscillation, t is time).
    Determine the maximum magnitudes of the -r and -[tex]\theta[/tex] components of the acceleration of the ends of the plunger during their motion.

    2. Relevant equations
    Vt = d[tex]\hat{u}[/tex]r/dt

    at = [tex]\omega[/tex]^2 (ro + sin (2[tex]\Pi[/tex]nt)

    3. The attempt at a solution
    So with the At equation that is above, it is really obvious that the max r component of the acceleration will be when the trig portion is its max or 1. So this happens when t = n/4. We can substitute [tex]\dot{\theta}[/tex] in for omega, but I am not quite sure what it means by the maximum magnitude of the theta component.

    Any hints would be appreciated, or if the direction I am headed in currently off.

    Last edited by a moderator: May 4, 2017
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted