Define evolution

[s41nn0n]

kul

 

[Mumbo]

wht question?

Read the post again, and stop being difficult. :/

 

[s41nn0n]

cant you just tell me?

 

[Mumbo]

I ninja-edited the post so that it would make more sense, but you read it too fast! Read it again!

It's 3:37 AM, I know literally nothing about physics, the discussion is getting ridiculous, and this entire argument is way off-topic. I'm done.

 

[FishFace]

Summary:

Meteors get hot and glow because they squeeze the air in front of them as they travel through the atmosphere. This heats up the outermost layer of the meteor to a very high temperature.
When the meteorite impacts the earth, if it doesn't disintegrate, this outer layer, because it is very small, quickly cools down. If you heat up a grain of sand to 10,000 degrees and drop it in a bucket of water, nothing much will happen. This is why meteorites are cool to the touch.

The upper atmosphere's temperature does not affect this, since at this point, the meteor's outer layer is extremely hot due to the ram pressure. -15 degrees of thin atmosphere isn't enough to make a dent in this.

 

[s41nn0n]

It will explode. Fishface. When something is heated to extream and cooled rappidly it will explode or shatter

 

[Elduran]

It will explode. Fishface. When something is heated to extream and cooled rappidly it will explode or shatter

Not always. It very much depends on the stress/strain relationships while temperature varies, and on the various other material properties.

Nothing is ever simple when generalising as to what something will do when subjected to a change in temperature!

 

[Loudmouth]

so how do you expain this?

Meteors have been in space for quite some time before getting to Earth. Space is cold, so the meteor is cold. When a meteor goes through our atmosphere friction is produced, but this friction only heats up the outer part of the meteor. The inside does not get heated in this process. When the meteor lands the cool interior of the meteor quickly cools the 1 mm or so of the fusion crust (the outer portion that actually melts during entry into the atmosphere). From here:

An object coming in through the atmosphere is known as a meteoroid, often seen as a fireball as the outermost surface is melted by frictional heating. The molten material is swept away from the meteoroid, exposing a fresh layer of material, which, in its turn, becomes heated and melts.

Eventually, however, atmospheric friction slows the meteoroid down, such that it is no longer travelling sufficiently fast for the outer layer to melt. At this stage, the outer layer quenches, forming a fusion crust. Examination of meteorites shows that this crust is very thin and is usually less than ~ 1mm thick.

The inside of the meteoroid has not been affected by heating, and meteorites are usually cool to the touch when they land. The fusion crust is a characteristic which aids in the recognition of meteorites.

Meteors, or shooting stars, are seen when tiny pieces of dust burn up in the atmosphere; no material is recovered from a meteor.
Particularly large numbers of meteors are seen when the Earth passes through meteoroid streams, in most cases cometary particles that are moving in orbits near those of the parent comet. Announcements about possibilities for meteor observations are made by the many national meteor organisations and through the International Meteor Organisation".​

 

[Loudmouth]

It will explode. Fishface. When something is heated to extream and cooled rappidly it will explode or shatter

This is caused by uneven heating or cooling.

 

[FishFace]

It will explode. Fishface. When something is heated to extream and cooled rappidly it will explode or shatter

Does rock spewed out of a volcano explode when it cools rapidly? Nope - molten rock dropped underwater just solidifies. So we wouldn't expect a meteor to explode, when it is, overall, much cooler than a lump of lava.

 

[s41nn0n]

First off all Glass is basically molten stones with other chemicals, and when glass is heated and then put into water it shatters.

 

[s41nn0n]

When was the moon created?

 

[Mavros]

When was the moon created?

is it so hard use wiki or at least google?

The formation of the Moon is believed to have occurred 4.527 ± 0.01 billion years ago, about 30–50 million years after the origin of the solar system.

 

[FishFace]

First off all Glass is basically molten stones with other chemicals, and when glass is heated and then put into water it shatters.

But you will have noticed that meteors are not made of glass, or similar brittle materials. They are made of rock and/or metal.

 

[Elduran]

First off all Glass is basically molten stones with other chemicals, and when glass is heated and then put into water it shatters.

I think you need to take a materials course before you spout any more nonsense. Saying that because glass is a mineral and rocks are minerals they should act the same is just plain silly.

"My glass is mate of atoms, and my tennis ball is made of atoms. I can play tennis with the tennis ball, therefore the glass should work just as well."

Sound sensible?

 

[Loudmouth]

First off all Glass is basically molten stones with other chemicals, and when glass is heated and then put into water it shatters.

Actually, it doesn't if done properly. This is how tempered glass is made.

 

[lemmings]

First off all Glass is basically molten stones with other chemicals, and when glass is heated and then put into water it shatters.

Glass shatters because it is highly susceptible to thermal shock. This occurs when a material has a low thermal conductivity, low tolerance for stress, and has a large amount of thermal expansion. Most meteorites that do survive the fall contain high concentrations of metals like iron. These metals both have high thermal conductivity and stress tolerance so they rarely detonate. There are examples however of meteorites exploding prior to impact such as the Tunguska event that destroyed over a thousand square miles of forest in 1908.

 

[Loudmouth]

There are examples however of meteorites exploding prior to impact such as the Tunguska event that destroyed over a thousand square miles of forest in 1908.

If I remember correctly, many scientists hypothesize that the Tunguska event was caused by a comet like body that was made mostly of water. The explosion was caused by the nearly instantaneous transfer of water/ice into steam.

 

[lemmings]

If I remember correctly, many scientists hypothesize that the Tunguska event was caused by a comet like body that was made mostly of water. The explosion was caused by the nearly instantaneous transfer of water/ice into steam.

Flash boiling requires a reservoir of superheated water that is contained under pressure. Friction would only heat the comet from the outside meaning that it will evaporate slowly as it enters the atmosphere and won’t create an explosion in midair.

 

[s41nn0n]

But you will have noticed that meteors are not made of glass, or similar brittle materials. They are made of rock and/or metal.

where? from the earth?