# Does Spin have rotational kinetic energy?

1. Oct 24, 2011

### Jeff Byram

I have two questions regarding rotational kinetic energy. I know that rotational kinetic energy is defined as:

KE = ½ I Ω^2

Where KE is the rotational kinetic energy [in units of: joules; kg*m^2/s^2], I is the Moment of inertial [in units of: kg* m^2], and Ω is angular velocity [in units of: radians/sec^2 or 1/s^2] so that the units check.

If (Electron or Nuclear) Spin is defined as J, with values equal to a half integer * h/2π, where h is Plank’s constant [in units of: Joule *seconds or kg*m^2/s],

#1, Is the rotational kinetic energy associated with Spin: KE = ½ J Ω ? (so the units check).

Since V = Ω R, where V is velocity, and R is the radius (or the Electron or Nucleus), so Ω = V/R, and since the fastest possible speed is the speed of light, c,

#2, Is the greatest possible rotational kinetic energy associated with Spin: KE = ½ J c/R ? (so the units check).