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Or does this only work as 'equal mass but not equal density'? Or rather, if I had a ball of tin 25,000 miles wide, and a ball of manganese 50,000 miles wide (we're talking spherical with no surface imperfections, equivalent in every way except in diameter) would they have the same gravitational pull?Bonus question, how important is density when relating to gravitational force?

So if an object made of manganese with an atomic number of 25 is twice the size as an object of tin with an atomic number value of 50, wouldn't this mean that the two objects would have an equal gravitational pull?

Twice the volume* ?

Quote from: Vereava on 24/10/2010 22:56:54Twice the volume* ?For cubes, it will be eight times. The volume of a cube is, strangely enough, the cube of the length of a side.The volume of a sphere is proporttional to the cube of it's radius, so, if you double the radius, the volume will also be eight times greater.

Quote from: Geezer on 24/10/2010 23:16:12Quote from: Vereava on 24/10/2010 22:56:54Twice the volume* ?For cubes, it will be eight times. The volume of a cube is, strangely enough, the cube of the length of a side.The volume of a sphere is proportional to the cube of it's radius, so, if you double the radius, the volume will also be eight times greater.so for theory's sake, Maybe it would be better if I used Beryllium and Germanium?New set up: a sphere of Beryllium that has a volume of 160,000 m^3 and a sphere of Germanium that has a volume of 20,000 m^3... Am I there yet?

Quote from: Vereava on 24/10/2010 22:56:54Twice the volume* ?For cubes, it will be eight times. The volume of a cube is, strangely enough, the cube of the length of a side.The volume of a sphere is proportional to the cube of it's radius, so, if you double the radius, the volume will also be eight times greater.

Quote from: Vereava on 24/10/2010 23:23:03Quote from: Geezer on 24/10/2010 23:16:12Quote from: Vereava on 24/10/2010 22:56:54Twice the volume* ?For cubes, it will be eight times. The volume of a cube is, strangely enough, the cube of the length of a side.The volume of a sphere is proportional to the cube of it's radius, so, if you double the radius, the volume will also be eight times greater.so for theory's sake, Maybe it would be better if I used Beryllium and Germanium?New set up: a sphere of Beryllium that has a volume of 160,000 m^3 and a sphere of Germanium that has a volume of 20,000 m^3... Am I there yet? I think so, but I've kinda forgotten what the question was []Assuming you picked volumes that will result in spheres of equal mass, then I believe they will have equal gravitational effects (if that was the question of course).

I was wondering if it was more about density rather than mass, because if two objects (made up of one substance each) are the same density, then they would have the same amount of mass, the only thing that would be different would be that one's diameter (in the case of beryllium and germanium) would be 8 times the size of the other... Same density.. same amount of matter.. different size objects.. same gravitational pull? Right? Even though one would be 1000 miles wide and the other is proportionally 8 times the size?

Quote from: Vereava on 24/10/2010 23:40:49I was wondering if it was more about density rather than mass, because if two objects (made up of one substance each) are the same density, then they would have the same amount of mass, the only thing that would be different would be that one's diameter (in the case of beryllium and germanium) would be 8 times the size of the other... Same density.. same amount of matter.. different size objects.. same gravitational pull? Right? Even though one would be 1000 miles wide and the other is proportionally 8 times the size?Ah, OK. For solid objects of uniform density, I think it's simply a question of the mass. The density has no effect.I say that because, in Newtonian Mechanics at least, you can assume all the mass of a solid object acts at it's center of gravity, which, in the case of your spheres, would be right at the center of each sphere. So, the actual volume of the object does not matter. It's only the quantity of mass that has an effect.

Think of the objects having an equal number of mols

So technically, you could have something the size of the sun pulling equally on something the size of a basketball?