Density problem

[atomic7732]

Ummm, I was trying to check out my Elode system's diagram of radius density... well... most of the small moons have really high density.

How does a Mass of .0008 moons and a diameter of .0007 moons give you just under 1 million g/cm^3?

[Laura]

That is a VERY low diameter for such a mass. It comes out at just under 100,000 g/cm³, though, not just under a million
You can't just take a fraction of a body's mass and expect a similar fraction of its diameter to produce a similar density as the original body. Volume of the object decreases a lot with any reduction of diameter - i.e. a sphere with half the diameter of the moon has far less than half the volume, so if you cram half the mass of the moon into that space, it's going to have to be at a crazy density

[atomic7732]

oh. I knew it had something to do with not being pefectly cubic.

[Dan Dixon]

I looked at this and think that the calculations are working correctly. Let me know if you suspect any further problems.

[Laura]

Yes, they are correct as they are.

The problem does manifest itself spontaneously when exploding an object, though, because then the fragments (which when added up represent the total mass of the originial) are forced to all be inside the volume of the original. That means less volume for the fragments, which in turn means higher density.