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: Kinetic energy and rigid bodies

  1. Nov 20, 2007 #1
    1. The problem statement, all variables and given/known data
    Does it make sense to talk about kinetic energy without specifying, which axis the body is rotation about? I mean, since K = ½ * I * w^2, I have to say that " ... the kinetic energy of the body around the x-axis is ...", right?
     
  2. jcsd
  3. Nov 20, 2007 #2

    nrqed

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Not only you have to say around what axis it is rotating but in addition you have to say around what point! In other words, you have to specify completely the axis around which the object rotates (and notice that the value of the moment of inertia depends on what is the axis around which the object revolves).
     
  4. Nov 20, 2007 #3
    Ok, good - then I have understood it correctly :-)

    Thanks!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook