# Motion in polar coordinates

• Oct 19th 2008, 01:26 PM
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Motion in polar coordinates
A particle is under the action of a central force F.(r, $\theta$) are polar coordinates in the plane of action so that $\textbf{F}=F(r) \textbf{e}_r$. I need to find F(r) given that $r(\theta)=\frac{a}{\sinh(\omega \theta)}$.

So $\ddot{r}-r\dot{\theta}^2=F(r)$ and the transverse component of the acceleration is 0.

Can someone help me solve the above using the definition of r to find F(r)?