# Particles trajectory in a bound orbit.

1. Dec 5, 2009

### sleventh

1. The problem statement, all variables and given/known data

I am to find the particles trajectory to the first order of r/a knowing it to have the Yukawa potential

v(r)=V$$_{\circ}$$r$$_{\circ}$$$$/$$r * e$$^{-r/r_{\circ}}$$
= -k/r * e$$^{-r/a}$$

2. Relevant equations

$$\theta$$(r)= $$\int$$ (1/r$$^{2}$$)/$$\sqrt{2\mu (E-U-l^{2}/2\mu r^{2}}$$) dr

3. The attempt at a solution

My attempt goes as far as using the effective potential given to have a basic equation of motion. I infortunately do not know what is meant by "to first order of"

any help or recomended readings would be greatly apreciated. im a bit lost.