# Can a particle of finite size escape from a black hole if it is overlapped with event horizon but not totally in it?

As we know, particles have finite size, if a particle, a part is inside the event horizon and the remain part is outside the event horizon, is it still considered as "unable to escape from black holes"?

Or in other words, when do particles considered as unable to escape from black holes? When it touches event horizon? A half of mass inside event horizon? Or totally inside event horizon?

• see this relevant question physics.stackexchange.com/q/160276 . Elementary particles do not have extent, they are points. Composites, including protons, would probably suffer the fate described in the answers. Feb 22, 2016 at 6:28

If your particle is some macroscopic object then it will simply be torn in half at the horizon. If we calculate the acceleration required to remain stationary at a distance $r$ from the black hole we get:
$$a = \frac{GM}{r^2} \frac{1}{\sqrt{1 - \frac{r_s}{r}}}$$
This goes to infinity as $r \rightarrow r_s$ so no matter how tough your material is it cannot resist the forces acting as we approach the horizon.