This is probably more of a math question, but it pertains to physics. Today in Classical Mechanics the professor was showing the following, F . dr = (MV2^2)/2 - (MV1^2)/2 but in great length, one of the steps along the way I did not understand how he did it... it was this: screw latex, if someone could please post a link to somewhere on the forums that shows how to use latex properly, I can't use it to save my life... here is the step with good old microsoft: [PLAIN]http://mynqa.com/Cargo/unk.bmp [Broken] My questions are, where did the number 2 come from in the denominator? Also, how did he bring in the velocity vector into the derivative like that? Thanks for any help.