5/6. Th. об изменении К энергии

$\tiny \frac{d(m\vec{\upsilon})}{dt}=\vec{F}\\ \vec{\upsilon}\frac{d(m\vec{\upsilon})}{dt}=\vec{\upsilon}\vec{F}\\ \vec{\upsilon}d(m\vec{\upsilon})=\vec{F}\vec{\upsilon}dt\\ d(\frac{m\vec{\upsilon}}{2})=\vec{F}d\vec{r}\\ \widetilde{d}A=\vec{F}d\vec{r}=F_{x}dx+F_{y}dy+F_{z}dz=F_{\tau}dS\\ \frac{m\vec{\upsilon}}{2}-\frac{m\vec{\upsilon_{0}}}{2}=_{M0M}\vec{F}d\vec{r}=A_{M0M}\\ \int : \vec{F}d\vec{r}=F_{x}dx+F_{y}dy+F_{z}dz=dU(x,y,z)\\ dU=\frac{\partial U}{\partial x}dx+... => \frac{\partial U}{\partial x}=F_{x} => \vec{F}=\vec{grad}U\\$