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Old September 14 2012, 11:36 AM   #6
Maurice
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Re: About planetary gravity

Think of it this way: an Earth-sized body made of the stuff the Earth is has 1g of gravity. An identically sized body made of collapsed star material is a white dwarf and about 200,000 as dense. So two objects of the same size only have the same mass if they are are made up of material of the same density.

Or try this...
The Sun has ~333,000 times the Earth's mass
  • On the surface of an object with the Sun's mass that is the size of the Sun, you'd weigh ~28 times what you do on Earth
  • But on the surface of an object with the Sun's mass that is the size of the Earth, you'd weigh 333,000 times what you do on Earth.

Why?

Density.

Explained here in pretty simple terms (link).


Alidar Jarok wrote: View Post
Gravity is a strange force. It's powerful enough to keep a giant chunk of rock rotating around the earth, but it's not powerful enough to prevent me from jumping into the air.
That's because you're forgetting to factor a burst of acceleration, which gravity quickly overcomes and pulls you back down.

Alidar Jarok wrote: View Post
[Jupiter's] gravity is strong enough to attract dozens of moons and would be crushing if we were to enter Jupiter's atmosphere.
At Jupiter's "surface" (where gas becomes liquid) gravity is only 2.54 time Earth's. Ergo, we wouldn't be crushed by Jupiter's gravity. We'd be crushed by the insane atmospheric pressures there.
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