Hi, Since velocity is a vector quantity I assume it follows that KE must also by a vector since KE=1/2mv squared. Is it true to say a rotating object has zero total velocity since + = - and therefore the total KE is zero? Thanks
No, because kinetic energy is not a vector quantity. It is a scalar. Think of the ##v^2## as coming from the vector dot product of the velocity with itself: ##v^2 = \vec v \cdot \vec v = v_x^2 + v_y^2 + v_z^2##. There is such a thing as rotational kinetic energy. http://hyperphysics.phy-astr.gsu.edu/hbase/rke.html