Honestly, I don't get it. People say it's because it's a postulate. But, I mean, I see people deriving the Schrödinger equation with the help of the wave function, $T+U$ and partial differentials in three space coordinates and one time coordinate. How is that not a derivation? And why can't the S...

I understand that the engine delivers power to the wheels and friction from the ground causes the wheels to roll. However, given the power(work per time) at the wheels, how does that energy become the kinetic energy of the car, since friction force from road doesn't do any work? Is it simply bec...