If  the gravitational force between sun and earth is inversely proportional to  $r^3$ , where r is distance between earth and sun. Then which of the following statements are correct.

1. Motion is in one plane by conservation of angular momentum
2.  $m{\omega }^{2}r=\frac{m{v}^2}{r}=\frac{{\left(mvr\right)}^2}{m{r}^3}=\frac{L^2}{m{r}^3}$
 
Let equilibrium radius be $\therefore (\frac{L^2}{m{r}_0^3}+\frac{K}{r_0^3})$  or  $K=\frac{L^2}{m}$
In general force on earth
$F=(\frac{L^2}{m{r}^3}-\frac{K}{r^3})\frac{dF}{dr}=(\frac{-3L^2}{m{r}^4}+\frac{3K}{r^4})$ 
 $\frac{dF}{dr}=3(K-\frac{L^2}{m})\left[\frac{1}{r^4}\right)=0$
This represents neutral equilibrium
3. Tidal forces are proportional to  $\frac{dF}{dr}$