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!

Total energy of a rolling sphere

  1. Nov 16, 2008 #1
    1. The problem statement, all variables and given/known data
    A solid sphere has a mass of 1.0 kg. It is rolling at a translational speed of 10 m/s. What is the total energy of the rolling sphere?
    I think I got the problem but I'm not sure I went about it the right way.

    2. Relevant equations
    I = (2/5)mr^2
    KE_rot = (1/2)Iw^2
    KE = (1/2)mv^2

    3. The attempt at a solution
    I assumed KE_total = KE_rot + KE...which I'm not sure is right.
    So...
    KE_rot = (1/2)Iw^2 = (1/2)(2/5)(m)(r^2)(w^2) = 20 Joules
    and...
    KE = (1/2)(m)(v^2) = 50 Joules
    soo...

    KE_total = 70 Joules
    This is the right answer, but I'm not sure if the total kinetic energy is actually the rotational kinetic energy plus the linear kinetic energy. Also...what is translational velocity? Is this any different than the sphere moving in a direction?
     
  2. jcsd
  3. Nov 16, 2008 #2

    LowlyPion

    User Avatar
    Homework Helper

    That's right.

    The translational velocity is the velocity of the center of mass.

    The rotational energy is about an axis through the center of mass.
     
  4. Nov 16, 2008 #3

    LowlyPion

    User Avatar
    Homework Helper

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Total energy of a rolling sphere
Loading...