Quick ?: Does density depend on gravity?

[MikeMike]

i dont believe it does, but cant find an easy answer online from google... or askjeeves...

 

[Corporate Thug]

no, mass / volume and mass is consistent no matter what gravity is right?

 

[NikolaeVarius]

Density=Mass/Volume

No

 

[silverpig]

Originally posted by: tenshodo13
Density=Mass/Volume

No

 

[gorcorps]

Originally posted by: Corporate Thug
no, mass / volume and mass is consistent no matter what gravity is right?

Correct. Some confuse weight and mass and they aren't the same thing. Weight is the force a certain mass has due to gravity (weight = mass * gravity contstant:9.81m/s^2)

 

[ItTheCow]

Yes/no.

Volume of a gas can change if gravity is great enough, but typically solids and liquids are unaffected

 

[MotF Bane]

Originally posted by: ItTheCow
Yes/no.

Volume of a gas can change if gravity is great enough, but typically solids and liquids are unaffected

 

[SlitheryDee]

Space is not all equally dense because gravity keeps matter in gigantic balls.

Edit: lol

 

[destrekor]

I would imagine a liquid would have a different volume at different gravities. Or is that completely dependent only upon atmospheric pressure?

I know any liquid water on the surface of mars would quickly "boil" away due to the lack of atmospheric pressure, quickly changing into gas.
Though gravity isn't crazy different on Mars.

I guess the question is: is atmospheric pressure and temperature the only factors in determining the molecular density?
Does liquid, as a phase, always maintain the same volume as long as the factors present permit it to stay in liquid form?

If we were to suddenly remove a large chunk of the middle of Earth, to reduce the gravity... yet keep the same atmospheric pressure - would the volume of a liquid change at all? Likewise, if we suddenly made Earth have a far greater mass, but kept the same atmospheric pressure - would it change then?

 

[ItTheCow]

Originally posted by: destrekor
I would imagine a liquid would have a different volume at different gravities. Or is that completely dependent only upon atmospheric pressure?

I know any liquid water on the surface of mars would quickly "boil" away due to the lack of atmospheric pressure, quickly changing into gas.
Though gravity isn't crazy different on Mars.

I guess the question is: is atmospheric pressure and temperature the only factors in determining the molecular density?
Does liquid, as a phase, always maintain the same volume as long as the factors present permit it to stay in liquid form?

If we were to suddenly remove a large chunk of the middle of Earth, to reduce the gravity... yet keep the same atmospheric pressure - would the volume of a liquid change at all? Likewise, if we suddenly made Earth have a far greater mass, but kept the same atmospheric pressure - would it change then?

For all practical purposes, liquids are incompressible (i.e., the volume does not change). On a microscopic level, yes the volume will increase in incredibly small amount.

 

[Jeff7]

Originally posted by: ItTheCow
Yes/no.

Volume of a gas can change if gravity is great enough, but typically solids and liquids are unaffected

Good thing you added "typically."

Your friendly neighborhood neutron star or black hole would like to disagree.

Originally posted by: destrekor
I would imagine a liquid would have a different volume at different gravities. Or is that completely dependent only upon atmospheric pressure?

I know any liquid water on the surface of mars would quickly "boil" away due to the lack of atmospheric pressure, quickly changing into gas.
Though gravity isn't crazy different on Mars.

I guess the question is: is atmospheric pressure and temperature the only factors in determining the molecular density?
Does liquid, as a phase, always maintain the same volume as long as the factors present permit it to stay in liquid form?

As far as engineering goes, liquids are considered to be incompressible. But if you really get down to it, even diamond will deform slightly when a force is exerted on it. For solids: Deformation = (Force * length)/(cross sectional area * modulus of elasticity)

But I was also told this in one of my classes: "An engineer will call a horse a sphere if it makes the math easier."
My favorite exampe of this was in bearing design. Apparently the equation for determining the 3-dimensional position or velocity or a particle in the lubricating fluid would be a differential equation with 60+ terms. Good luck solving it in this lifetime.

So some assumptions are made - various terms are said to be nearly zero, and the solution is examined in only two dimensions. That makes it solvable in a reasonable timeframe. But the answer's not quite as accurate. Kind of like Newtonian physics. They ignore relativistic effects, but since those fun effects, such as time dilation and mass change due to velocity, are so nearly zero, they can be safely ignored in most cases.

If we were to suddenly remove a large chunk of the middle of Earth, to reduce the gravity... yet keep the same atmospheric pressure - would the volume of a liquid change at all? Likewise, if we suddenly made Earth have a far greater mass, but kept the same atmospheric pressure - would it change then?

Yes, it would change, but slightly. I'm sure water does have a very well-quantified compressibility coefficient, or value, or stiffness, or whatever it's called.
And the resulting change in volume could be calculated.