Mekanik, kinematik

Det skall nog vara $\frac{d\overrightarrow{r}}{d\theta }\frac{d\theta }{dt}$.

$\frac{d\theta }{dt}=\omega$.

$\frac{d\overrightarrow{r}}{d\theta }=\frac{d}{d\theta }\left(\frac{b}{\sin \theta }{\overrightarrow{e}}_r\right)$$=-\frac{b}{{\sin }^2\theta }·\cos \theta {\overrightarrow{e}}_r+\frac{b}{\sin \theta }\frac{d{\overrightarrow{e}}_r}{d\theta }$.

Varvid $\frac{d{\overrightarrow{e}}_r}{d\theta }={\overrightarrow{e}}_{\theta }$.

Tillägg: 26 mar 2024 23:06

Kedjeregeln. $\frac{d\overrightarrow{r}}{dt}=\frac{d\overrightarrow{r}}{d\theta }\frac{d\theta }{dt}$.