
#1
Sep613, 05:45 AM

P: 50

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 



#2
Sep613, 05:56 AM

Mentor
P: 11,228

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.phyastr.gsu.edu/hbase/rke.html 


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