When Did It Explode?

[Ian Moulding]

So it's a super-sized ice-covered terrestrial planet orbiting a red star...

Krypton!

[Rkolter]

I've always wondered what a rocky, terrestrial planet with 10 or more times the Earth's mass would look like.

Aside from being frigging huge, the gravity involved suggests to me that there would be minimal major surface features.

Very cool.

[Killbert-Robby]

I've always wondered what a rocky, terrestrial planet with 10 or more times the Earth's mass would look like.

Aside from being frigging huge, the gravity involved suggests to me that there would be minimal major surface features.

Very cool.

I always wanted to say this :









I concur

[Ian Moulding]

More astronomical neatness...
http://www.space.com/scienceastronomy/a ... 10607.html
http://www.space.com/scienceastronomy/0 ... _zone.html
http://www.space.com/scienceastronomy/0 ... lanet.html

[Dutch!]

Cool.

Or freezing, whichever fits best.

[Kilre]

I've always wondered what a rocky, terrestrial planet with 10 or more times the Earth's mass would look like.

Aside from being frigging huge, the gravity involved suggests to me that there would be minimal major surface features.

Very cool.

i'm curious. why would there be fewer surface features?

[Ian Moulding]

Gravity. It would take more energy to build mountain ranges on a high-gravity planet, and they would tumble down faster (And harder) than they do here on Earth.

On the other hand, a massive planet may have a hotter core due to heat generated by compression, which would mean more geologic activity. The mountain ranges form quickly, but they don't rise as high as on Earth. So the surface may be corrugated, covered in lots of low wrinkles like the Canadian Shield.

Also, I'm kind of geeking out today. http://news.bbc.co.uk/2/hi/science/nature/4801968.stm

[Rkolter]

Gravity. It would take more energy to build mountain ranges on a high-gravity planet, and they would tumble down faster (And harder) than they do here on Earth.

On the other hand, a massive planet may have a hotter core due to heat generated by compression, which would mean more geologic activity. The mountain ranges form quickly, but they don't rise as high as on Earth. So the surface may be corrugated, covered in lots of low wrinkles like the Canadian Shield.

It would only mean more geologic activity if the core was of a size large enough to warm the entire giant mantle of the planet to where it would be gooey enough to allow for hot spots. Remember the reason the Earth has geologic activity is that we have a thin spot in our crust at the ocean bottoms. Without that thin spot, the heat might dissipate without causing any sort of mountain building at all.

Now, as the planet cooled, it would shrink, and THAT would cause mountains to form. Hm.

[Czar]

Hey kolter, science question time: How do you calculate surface gravity mathematically if you know a planets diameter and mass?

[Jim North]

Magic Pixies!

[Sortelli]

Nudity!

[Rkolter]

Newton's forumula for universal gravity:

F=GMaMb/r^2

If we're talking about a really tiny mass for the second object (for example, you vs. the planet) you can simplify it by removing the smaller mass.

F=GMp/r^2

F is the force of gravity, G is the gravitational force constant, Mp is the mass of the planet, and r is the radius of the planet.

Incidentally, once you have F you can calculate the acceleration due to gravity, a:

a=F/Mp

[Dburkhead]

Newton's forumula for universal gravity:

F=GMaMb/r^2

If we're talking about a really tiny mass for the second object (for example, you vs. the planet) you can simplify it by removing the smaller mass.

F=GMp/r^2

Sorry rkolter, but you cannot "simplify" it that way. What you've just done is replaced m with unity which you will readily see quickly gets you the wrong answer (particularly once you consider that the units now no longer work.)

F is the force of gravity, G is the gravitational force constant, Mp is the mass of the planet, and r is the radius of the planet.

Incidentally, once you have F you can calculate the acceleration due to gravity, a:

a=F/Mp

Instead of simply dropping the small mass, you do a substitution:

F = ma and the small masses on both side of the equation cancel so you are left with

a = GMp/r^2

[Rkolter]

Newton's forumula for universal gravity:

F=GMaMb/r^2

If we're talking about a really tiny mass for the second object (for example, you vs. the planet) you can simplify it by removing the smaller mass.

F=GMp/r^2

Sorry rkolter, but you cannot "simplify" it that way. What you've just done is replaced m with unity which you will readily see quickly gets you the wrong answer (particularly once you consider that the units now no longer work.)

Eeg...

I meant to explain it as 'you can calculate the surface gravity of the planet without really worrying about your own mass'. But you're right, dropping the second mass prevents you from getting kg^2. You could assume the second mass was one kilogram for the purposes of the equation though, thus effectively removing the mass of the second object from the equation.

My goal was to stop people from saying, "I weigh 150 kilograms so I should feel much more gravity than a potato that weighs 1 kilogram - that potato should almost be floating!" - the kind of questions I get on Reasoned Cognition.

Quote:
F is the force of gravity, G is the gravitational force constant, Mp is the mass of the planet, and r is the radius of the planet.

Incidentally, once you have F you can calculate the acceleration due to gravity, a:

a=F/Mp

Instead of simply dropping the small mass, you do a substitution:

F = ma and the small masses on both side of the equation cancel so you are left with

a = GMp/r^2

Gah. This is what I get for posting early, and for answering math questions in the forum. dburkhead's right folks.

acceleration = F/Mapple = (GMpMapple/r^2)/Mapple = GMp/r^2

[Dburkhead]

Newton's forumula for universal gravity:

F=GMaMb/r^2

If we're talking about a really tiny mass for the second object (for example, you vs. the planet) you can simplify it by removing the smaller mass.

F=GMp/r^2

Sorry rkolter, but you cannot "simplify" it that way. What you've just done is replaced m with unity which you will readily see quickly gets you the wrong answer (particularly once you consider that the units now no longer work.)

Eeg...

I meant to explain it as 'you can calculate the surface gravity of the planet without really worrying about your own mass'. But you're right, dropping the second mass prevents you from getting kg^2. You could assume the second mass was one kilogram for the purposes of the equation though, thus effectively removing the mass of the second object from the equation.

My goal was to stop people from saying, "I weigh 150 kilograms so I should feel much more gravity than a potato that weighs 1 kilogram - that potato should almost be floating!" - the kind of questions I get on Reasoned Cognition.

But you do feel much more gravity than the potato. That's why you weigh what you weigh and the potato weighs what the potato weighs. The "amount" of gravity that you feel is what we call "weight."

[Rkolter]

Eeg...

I meant to explain it as 'you can calculate the surface gravity of the planet without really worrying about your own mass'. But you're right, dropping the second mass prevents you from getting kg^2. You could assume the second mass was one kilogram for the purposes of the equation though, thus effectively removing the mass of the second object from the equation.

My goal was to stop people from saying, "I weigh 150 kilograms so I should feel much more gravity than a potato that weighs 1 kilogram - that potato should almost be floating!" - the kind of questions I get on Reasoned Cognition.

But you do feel much more gravity than the potato. That's why you weigh what you weigh and the potato weighs what the potato weighs. The "amount" of gravity that you feel is what we call "weight."

Yeah. I know that. But they didn't ask what your weight might be on the planet. They asked only what the surface gravity of the planet might be. Some tangents are best left unfollowed. The next question would be, "So what's the difference between weight and mass." And so you explain that. Then, "So do I weigh less in an elevator going down?" And you explain that Einstein specifically used that as an example and yes you would weigh less. Then they ask why you don't weigh anything in space when you could use the same equation to determine the "surface gravity" 100 miles up just by adding 100 miles to the radius. You explain that you weigh nothing because you're technically falling but that you still have mass. Then they ask the whole 'if I have more mass than a potato and we both jump out of an airplane, and gravity works MORE on me than the potato, why don't we hit at seperate times? When you explain that, they ask about a 100 kilogram sheet of metal and a 100 kilogram person, and you explain surface area and that air resistance causes the sheet to slow, and then they ask how big the holes you make will be when you hit the ground, and you try to explain that and that the density of the ground matters, and they ask about if you fell faster and you say that would depend on gravity and so finally they ask... "Well, how do I work out the surface gravity of the planet anyway?"

[Dburkhead]

Then you demonstrate by dropping them out of an airplane. Sheesh.

Didn't they teach anything at that grad school of yours?

[Garneta]

Magic Pixies!

Nudity!

How about just using nude magic pixies?

[Rkolter]

Magic Pixies!

Nudity!

How about just using nude magic pixies?

Or a nude sortelli.

[MixedMyth]

Thats....big.

Reminds me, though. After watching Smallville, I have concluded that the town is not in fact in Kansas. It's in New Jersey.

And then suddenly everything makes sense.