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: Solid cylinder- please help

  1. Mar 14, 2007 #1
    1. The problem statement, all variables and given/known data
    This problem consists of 3 parts. Though my trouble in only part 3, I figured that by providing all of the part might show someone clues that I might have missed....

    1. If instead of the force F an actual mass m=.0630 kg is hung from the string, find the angular acceleration of the cylinder. (I answered this correctly)

    2. How far does m travel downward between .590s and .790s after the motion begins (answered this one as well)

    3. The cylinder is changed to one with the same mass and radius, but a different moment of inertia. Starting from rest, the mass now moves a distance .0362 m in a time .510s. Find Icm of the new cylinder.

    2. Relevant equations

    a.) K=1/2*M*Vcm^2 + 1/2*Icm*w^2
    b.) K1 + U1 =K2 +U2
    c.) Vcm= Rw

    3. The attempt at a solution

    First I used equation a. to try to get Icm by itself.
    2(Mgh -1/2MVcm^2)/w^2 =Icm
    Then I used equation b to get w by itself, changing the above equation to:
    2(Mgh -1/2 MVcm^2)/ (Vcm/R)^2 = Icm

    At this point I realized that I don't know what the new mass and radius is, just that it is the same value. Also, I do not know what Vcm is. Plus, the fact that the problem provides the time it takes for the object to descend makes me think that I am missing a step since I have yet to apply it.

    This particular homework problem is due tomorrow so I hope that I have provided enough information that someone can explain whether or not I am on the right track, etc.
  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