1. Not finding help here? Sign up for a free 30min 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!

A rolling hollow sphere

  1. Dec 6, 2006 #1
    A hollow spherical shell with mass 1.50kg rolls without slipping down a slope that makes an angle of 40.0degree angle with the horizontal.
    -Find the magnitude of the acceleration of the center of mass of the spherical shell

    I am really confused on how to go about this problem. I know it has to do with inertia, but wow, i just don't know where to start.
  2. jcsd
  3. Dec 7, 2006 #2
    U used the term 'rolls without slipping'. I thought of using rotational mechanics to solve it but u are not given the radius of the spherical shell. Thus, i shall treat it like a case of linear motion down the slope. Resolving forces and applying Newton's 2nd law on the shell, we have Normal reaction force = mg cos 40 and mg sin 40 = ma. Thus a = g sin 40 = 9.8 sin 40. If u want to find angular acceleration of the shell, u need to have the shell's radius and use the relation, linear acceleration = spherical radius x angular acceleration.
  4. Oct 22, 2007 #3
    No, you don't need the radius for this one. This is a hollow shell and it's moment of inertia is 2/3mr^2 = I
    Fy = 0
    Fx = mgsin(theta) - f = ma_cm

    I get from Fx=mgsin(theta)-f=ma_cm (1)
    and fR = 2/3mra_cm (2)

    Solve f from (1).
    Substitute that into (2) and then solve for a_cm

    I get a_cm = (3gsin(theta))/5
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: A rolling hollow sphere