# Collision question

1. Feb 6, 2005

### googolplex

This question is kind of strange, but I'm fascinated by it... Say an asteroid 10km in diamter crashes into the north pole at a right angle with a velocity of 0.99c!! I imagine that it would punch through the whole planet and whatever is left will exit from the south pole, creating a temporary tunnel. Would the "exit hole" be much larger than the asteroid itself? Would there be a substantial amount of gamma radiation/particle production? What would be left of the asteroid? Elementary particles and radiation? What kind of an effect would this have on the earth and its biosphere? A related question is: if a drop of water 1cm in diameter collides with a huge (and very thick) steel wall at 0.99c, what would happen? How large of a "dent" would it make?

2. Feb 6, 2005

### Cyrus

Hmm, I know that waterjets are used to cut though pieces of metal under very high pressures. I wonder why the water does not vaporize at such high speeds, maybe it shoots at such a small distance there is no time for it to vaporize before it hits the piece of metal. The same might apply for your question, if water could travel that fast without something happening to it. Also, for the case of the asteroid, I dont think its practical to talk about anything of that size traveling at .99C, so to comment on how it would impact would be meaningless. I do remember seeing on tv once that when a BIG, asteroid collides with a plannet, its not a big kaboom, like in the movies, but its actually a quite slow impact. It creates big nasty shock waves and earth quakes, vaporizes the atmosphere and does a whole bunch of other nasty things to the inhabitants.

3. Feb 6, 2005

### krab

Last question first: Such a droplet of water would have an energy of over 300 TeraJoules, or more than 5 times the energy that was released by the Hiroshima bomb. So, you could wipe out a city with it. So scaling up, your 10km asteroid, would have over more energy yet. It would vapourize earth.