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Why are meteors hot?


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2 hours ago, Yunru said:

K.E.=0.5MV^2

That's gotta go somewhere. 

You wrote what I planned to write. It's the same as brake discs. You transfer energy from kinetic (movement) to heat. If we look at perhaps the most famous meteor crater (the one, which killed the dinosaurs), the bedrock acted like a liquid on impact, sprayed out to all sides and once in the air, it cooled and we have rocks in droplet form today. The bedrock wasn't heated by friction in the atmosphere and it was instant on impact meaning it didn't really have time to transfer heat from the meteor.

Also you just revealed you have no work experience in a metal workshop. If you bend a pipe or metal plate without heating it up, it will heat up itself in the bend due to the internal friction caused by "the impact". Not enough to really make a difference, but if you put your hand on it, you can tell it's a bit hotter than when you started and the rest of the metal. You have to be a bit quick though since metal usually has a high internal conductivity and the heat spot will spread the heat quickly across the entire metal piece.

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Thanks all for the thoughts - kinetic energy is certainly the most plausible reason, if not explaining why they're on fire prior to collision. The reason I was asking was out of consideration of modding them to include some ice as an early-game source of water in a skyblock-like experience. I may just have them "collide slower" to reduce that heat so the ice doesn't immediately melt.

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1 hour ago, Gurgel said:

Flaming things falling from the sky are just sooo much cooler than chunks of ice!

Oh I would LOVE for the game to incorporate falling chunks of ice!  Sudden catastrophic icy floods if you did not deal with it right away!

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Thinking about this, meteorites picked up from the ground on Earth are cold right after landing...they've been floating around in space for eons, and when they hit the atmosphere, I think it's the air that gets hot because of the air pressure of the meteor hurtling through the atmosphere...that heat isn't enough to counteract the coolness of the rock (acts almost as a barrier). Most are small and only hit the ground at terminal velocity anyway, so again, after the fireball, the air cools them down as they fall.

Soooo...I guess the meteorites in ONI may be hot, as they hit the surface at full speed, and maybe the speed of that impact causes enough friction to heat the rock.

Probably...maybe...someone more science inclined might have a better answer.

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3 hours ago, JesusOnEez said:

Thinking about this, meteorites picked up from the ground on Earth are cold right after landing...they've been floating around in space for eons, and when they hit the atmosphere, I think it's the air that gets hot because of the air pressure of the meteor hurtling through the atmosphere...that heat isn't enough to counteract the coolness of the rock (acts almost as a barrier). Most are small and only hit the ground at terminal velocity anyway, so again, after the fireball, the air cools them down as they fall.

Soooo...I guess the meteorites in ONI may be hot, as they hit the surface at full speed, and maybe the speed of that impact causes enough friction to heat the rock.

Probably...maybe...someone more science inclined might have a better answer.

Well there is an entire field of science that deals with this, basically regular friction doesn't work as we understand it at these speeds. So that complicates the matter of "how hot will it be when it touches down". If you wanna know more about this, try to look up how coming back to earth works on re-entry vehicles. I recommend this video:

The meteorites in ONI are a bit simpler to calculate because there is no atmosphere outside the asteroid, therefore the energy of the impact has only a couple places to go 1) friction and 2) bouncing off. But since the meteorites basically just deposit without any ejecta you can take out the bouncy part. So in our simulation the energy can go only one place and that is heating of the matter through friction. So depending on how fast the meteorites impact with there is no limit to how hot they can get. I made this calculation once before on this forum and if the meteorites were to hit with a realistic speed of a few km/s the temperature would get high enough to just boil the entire meteorite. Not saying they should be this hot, but essentially any temperature can be chosen and then physically justified with "that's what a meteorite with that speed would do." So in this case realism can never get in the way of balancing or vice versa..

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3 hours ago, JesusOnEez said:

meteorites picked up from the ground on Earth are cold right after landing

Do you have any source on this? Every single source I have read states that meteors are hot after impact.

I read a report about some girl being hit by a rock. She didn't see who threw it at her, but because it looked different, she decided to take it with her. She was surprised that it was hot. It wasn't until years later that she learned it was a meteor, which was so small and had slowed down enough to not really cause injury in impact.

This mean small slow meteors are hot. Big meteors might be too big to heat up by friction, but they have a tendency to explode on impact because they don't slow down. This leaves the question: which kind of meteor is cold after impact?

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