So this is a spin-off from the "How could we see an approaching black
hole" thread...

Small black holes could exist, say the theorists.

Let's consider a really small black hole - say, 100kg in mass. This
would have a very, very, very small event horizon. Were it to impact
the earth, dead-on, at the same sort of speed that we would expect
asteroidal or cometary impacts, what would happen?

Would there be any resistance to its passage?

Woud it come to rest or bore straight though?

If the former, would it eventually absorb the entire earth, and if so,
how long would "eventually" be?

If it went straight through, how big a hole would there be in the
earth on exit?