D

#### dock

(1)if you define dx/dt as V the do you neceserily agree that x is function of V and t?

(2)if so then why do you derivate x partially only by dt?

(3)what is dx/dV then?

(4)how do you measure the momentary speed V if V=dx/dt?

your physics needs to be redone. i mean it most sencerely.