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Discussion Starter #1
Three objects made of iron are traveling through space at 40,000 mph. One is the size of an orange. One is the size of a trash can. One is the size of a school bus. They all hit the earth's atmosphere at the same time, the same speed, and the same angle. All three crash on the surface of the earth. Assuming none of them burn up, which one hits the ground first?

Bonus questions:

How large does a meteorite have to be in order to be called an asteroid? Have you ever seen a meteoroid? How far from Earth can a meteor exist?
 

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In a pure vacuum, they would all hit at the same time, but the atmosphere will slow the bigger objects due to friction. You didn't specify whether the sizes of these pieces of iron were solid or hollow, but I would say the orange size one would hit first while the other two are slowed down ever so slightly from their frontal surface area.

No idea on any of the bonus questions.
 

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Given your other conditions, the object with the least air resistance hits first (so the orange)

Bonus: A Meteorite is something that has entered and survived burning through the Earth's atmosphere and lands on the surface. If you are talking about a small object in space it is properly called a Meteoroid. If you are talking about a Meteoroid vs an Asteroid, memory says something like 4 yards in diameter but I don't remember if that is right.
 

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If all the objects are the same material and density and shape, they will experience air resistance that is in the same proportion to their mass and therefore will fall through the atmosphere at the same speed and hit the ground at the same time. Although there is a difference in their reynolds numbers which might give a very slight speed advantage to the largest object.

I agree with Dutch on the bonus information. I have seen a meteorite in a museum, but meteroids are hard to observe since they are in space and small. A meteor has to be close enough to the Earth to be in the atmosphere.
 

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Discussion Starter #6
I may need to look further into the bonus question. Barry has the correct answer for meteor. But I thought a meteoroid was a meteorite that survives entry and lands. Maybe I have it backwards.

I gave the first question to an old friend who got it right, but he said he was guessing. Over 90% get it wrong, maybe 99%. The best clue is found in Northern Arizona, and it's two miles wide.
 

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I have a knife that has a meteorite bolster. It's really neat-looking metal with a unique crystalline texture.

 

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(For simplicity's sake, assuming they're roughly spherical...)

The aerodynamic drag force is proportional to an object's area, which is proportional to the square of the diameter.

Mass and momentum (or the ability to resist deceleration per a given force) for an object with a given density are proportional to the object's volume, which is proportional to the cube of the diameter.

Force ∝ Diameter^2

Mass ∝ Diameter^3

Acceleration = Force / Mass

Therefore...

Acceleration ∝ Diameter^(-1)

Therefore a larger object of similar density will decelerate more slowly due to atmospheric drag and hit the Earth first.

The "school bus"-sized object will hit first.


(A mental trick to questions like this that can often be helpful is to take the given examples to extremes. So, instead of comparing a small-ish, medium-ish, and large-ish object, compare a microscopic object to a gigantic object.

For example: If this same question was instead posed as comparing a tiny spec of iron the size of a piece of dust vs a giant iron sphere 1 mile across, it's obvious/intuitive that the giant sphere would plow through the atmosphere while barely slowing, and the piece of iron "dust" would quickly slow to only a few mph.)
 

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Discussion Starter #11
Yes. jsmay is correct. They discussed this in the two Hollywood's movies; Deep Impact and Armageddon. Objects of a certain size, like the one that hit Arizona, are not slowed down by the atmosphere. It's like when we were kids and tossed small rocks into streams or ponds. We could watch the stones glide to the bottom. But when we dropped a huge boulder in, they went straight to the bottom (ker-plunk).

What is interesting, although I can't recall the exact size, is there is a specific size where the object entering earth's atmosphere will slow down. When you get any larger than a certain size of object, it won;t be slowed down. I might have to go visit the giant meteor crater visitors center again to find out what that size is.

I have an even more difficult puzzler, if you are interested.

When we look at the sun, there is what we call the visible surface, from where the corona extends into space. The center of the sun, where heat is generated, is approximately 27 million degrees. The surface of the sun is said to be 10,000 degrees. If you travel a million miles away from the sun's visible surface, what is the temperature?

What is the second law of thermodynamics?
 

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I have an even more difficult puzzler, if you are interested.

When we look at the sun, there is what we call the visible surface, from where the corona extends into space. The center of the sun, where heat is generated, is approximately 27 million degrees. The surface of the sun is said to be 10,000 degrees. If you travel a million miles away from the sun's visible surface, what is the temperature?
It depends which direction you go and if there happens to be a celestial body exactly a million miles away. But the odd are you would be in space where the temp is absolute zero.
 

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Discussion Starter #15
Several million degrees (temperature of plasma in the Corona)
Follow up question: How do temperatures get to 1,000,000 Kelvins, even as high as 10,000,000 Kelvins, as far as a million miles away from the suns visible surface, which is 10,000 degrees? I mentioned the second law of thermodynamics because scientists have difficulty explaining a phenomenon that violates this law.
 

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Follow up question: How do temperatures get to 1,000,000 Kelvins, even as high as 10,000,000 Kelvins, as far as a million miles away from the suns visible surface, which is 10,000 degrees? I mentioned the second law of thermodynamics because scientists have difficulty explaining a phenomenon that violates this law.
Jets of plasma known as spicules, which are fountains of plasma, are propelled upward from near the surface of the sun into the outer atmosphere.
 

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Where did you pick this up......so awesome....I want one!!!!!
It is a one-of-a-kind custom made by Matt Cucchiara. At $15/ gram, this material is anything but cheap. You have to really want it. I'm a knife collector and have many custom knives.
 

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Discussion Starter #18
Jets of plasma known as spicules, which are fountains of plasma, are propelled upward from near the surface of the sun into the outer atmosphere.
As good a guess as any. But the correct answer is, and it's one reason I love science, nobody knows. Nobody has ever come up with an explanation that does not violate the second law of thermodynamics. You move away from a source of heat and it gets cooler, always, except in this instance. How great is that? An unsolved mystery of science. Of course there was one man who knew the answer, but we hung Him on a cross before He shared all the secrets He knew.
 

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Good brain teaser. Congrats to jsmay on the correct answer to the first one, and also a good explanation as to why. I once drove past the exit to Meteor Crater, AZ, but failed to stop in. If I'm ever out there again, I will be sure to check it out.
 

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It is a one-of-a-kind custom made by Matt Cucchiara. At $15/ gram, this material is anything but cheap. You have to really want it. I'm a knife collector and have many custom knives.
I don't get it. Which part is meteorite? I don't see any different material between the blade and the handle.
 
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