At interplanetary speeds (roughly 11 km/s [Earth escape velocity] to 72 km/s [orbiting at Earth speed in the opposite direction]), it would easily liquify (and then devour) the planet. At intersteller speeds, it might be able to pass all the way through.
Fake-edit: putting the numbers into the kinetic energy formula, an 11 km/s impact would yield 8.891 x 1032 joules, enough to liberate every particle of the planet from the gravity of every other particle (although it's only four times the required amount). That's without adding the mass of the black hole, though, so it may not quite be enough.
The minimum velocity needs to take into account the Sun's gravity well (take a parabolic orbit with 1AU aphelion).
For the maximum speed, the sky is the limit. That is to say it could be anything up to a significant fraction of c depending on how it came to travel through the interstellar space.
You can't just use the kinetic energy formula as you need a process to transfer it to the body it collides with. It's got the mass of the Moon, but it's not a ball of rock.
The two probable modes of destruction would be ripping away a significant chunk of Earth and releasing significant energy through accretion. How serious of an effect would each of those have needs to be calculated.
I find this problem to be a bit more complex than I'm comfortable with, but I might get back to it later, after a couple of beers.
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Topic: The Insane Physics Thread. (Read 16750 times)