# Central Force Orbit with Polar Coordinates

1. ### schrau24

1
I have this question:

A particle of mass m moves under the influence of a central force; F = -grad (V) where V(r) is the potential energy. Angular momentum is conserved because the force is central. The constants of motion are L and energy E.

We use polar coordinates r(t) and θ(t) to describe the motion. Derive an equation for dr/dθ as a function of r. [The solution of this first-order differential equation determines the orbit.]

Does anyone know how to do this?

Thanks!