= Why kinetic energy is $mv^2/2$?
* why the square: https://physics.stackexchange.com/questions/535/why-does-kinetic-energy-increase-quadratically-not-linearly-with-speed on <Physics Stack Exchange>. <Ron Maimon>'s answer is great, as it relies only on the following staring points:
* <energy is conserved>
* <Galilean invariance>
He also offers a <symmetry> argument considering the case of <potential energy>.
* why the half: https://physics.stackexchange.com/questions/27847/why-is-there-a-frac-1-2-in-frac-1-2-mv2 on <Physics Stack Exchange>
Others:
* https://physics.stackexchange.com/questions/156696/why-is-kinetic-energy-defined-as-1-2m-v2