We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).
Gp wasn't suggesting computing energy, just pointing out that a bare mv results in a vector, not a scalar that can be easily compared. What we want is m|v|, which can be computed as m * sqrt(v^2). And anway, for "energy" computation purposes mv^2 will get you double the "true" figure (assuming you were interpreting it as kinetic energy), since K.E. = 0.5 * m * v^2.