Assume, you are the defense expert for trucking company. The plaintiff's attorney asks you in your deposition ..... "isn't possible that the transmission failed on top of the hill and the truck began a free run down hill and crashed killing the driver"?. And you honest guy answer: " yes " {because anything is possible! But this thinking has nothing to do with YOUR case. If the opposing Attorney had ask:.."WASn't it possible etc." you would not stumbled into his trap!. See Chapter 4 of my book,'Forensic Expert' for all things a good expert knows and does and does not do. Remember, most experts with Ph.Ds and more, have never repaired a brake or steering system or never did any mechanical work for a living. They finished high-school, went to a university yet never designed a weld or dynamically loaded bolt connection. They probably know why the kinetic energy equation only uses half the mass, that is m/2 (see page 21-9 for the derivation of E = (m/2){VxV}.