
For zero energy, $E=0$, we derive exact, classical solutions for {\em all} powerlaw potentials, $V(r)=\gamme/r^\nu$, with $\gamme>0$ and $\infty<\nu<\infty$. When the angular momentum is nonzero, these solutions lead to the orbits $\r(t)=[\cos\mu(\th(t)\th_0(t))]^{1/\mu}$, for all $\mu\equiv\nu/21\ne0$. When $\nu>2$, the orbits are bound and go through the origin. This leads to discrete discontinuities in the functional dependence of $\th(t)$ and $\th_0(t)$, as functions of $t$, as the orbits pass through the origin. We describe a procedure to connect different analytic solutions for successive orbits at the origin. We calculate the periods and precessions of these bound orbits, and graph a number of spercific examples. Also, we explain why they all must violate the virial theorem. The unbound orbits are also discussed in detail. This includes the unusual orbits which have finite travel times to infinity and also the special $\nu=4$ case.

