system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why would a giant asteroid hitting earth cause so much damage? Wouldn't it just crush the area where it lands and that would be it?
gpt
An asteroid with a size at which air resistance becomes entirely negligible would impact the Earth at over 10 km/s, releasing all its kinetic energy. Since asteroids are both really damn massive and impact at such a velocity, their kinetic energy is huge, and releasing that amount of energy triggers effects through both the Earth's crust and through the atmosphere of significant magnitude.

But really, an asteroid would absolutely wipe out the impact area (greater than the size of the asteroid), but, kinetically, it would't do much to the rest of the world. It can trigger decent tidal waves, but most of the inland areas would be immune to that as well.

However, it would kick up a huge amount of soil into the atmosphere that would stay there, darkening the sky, absorbing sunlight and creating a "nuclear winter" through most of the world, that would be catastrophic to the biosphere, as plants can no longer properly sustain themselves and most of the food chain collapses.