Kinetic energy for extended object

[ryanmartinneutrino]

The momentum and CM chapter should have something to show that the kinetic energy of an extended object is 1/2Mv_CM^2, or at least there should be a question library question to show that.

[ryanmartinneutrino]

actually, make this a question library problem - I put the derivation in the total kinetic energy of a translating + rotating object. A question lib problem without the rotating part should be straightforward-ish.