User blog:Cerne/Relative density

I have gotten most of my planet's physical stats decided now, and I do not believe the orbital stats will be that much of a problem. They can be determined pretty easily online, as can information on my planet's sun and moons. There is only the slight matter of polar flattening and precession to figure out. The equations required for polar flattening, as well as polar gravity, can be found on Geoff's site. The equations on the site ask for planet density and I already have mine set at 7452 kg/m3, but unfortunately it asks for a relative value rather than the actual density. The site says "relative to the Earth" but I am not sure if that means relative to the Earth in comparison to the density of water - which would be 5.5 - or the Earth itself. If the latter, then the number I would have to work with would be 1. It may not be, but I am going to go with that for now so if it ends up not making sense, at least you will know why.

Earth's density is 5515.3 kg/m3 but I am rounding the 0.3 down to make the number easier to work with. My planet's density, again, is 7452 kg/m3. Taking 5515 away from 7452, I get 1937. This is 35.1223935% of 5515, and it goes into that number 2.84718637 times. Here are a few more equations that I used to verify those numbers, if only for the sake of recording my progress:

7452 - 5515 = 1937

5515 + 35.1223935% = 7452

1937 x 2.84718637 = 5515 & 5515 / 2.84718637 = 35.1223935%

100 / 2.84718637 = 35.1223935

So upon rounding my percent difference down I get 0.35 which is 35% higher than Earth's relative density of 1. Therefore I will use 1.35 as my planet's relative value for density. If it turns out that Earth's relative value is 5.5 instead, then I will use 5.85. I am not sure if that sounds right, though, given my miserable proficiency in mathematics. If anyone has been to Geoff's site or any other site, knows what he is talking about and sees any errors, please reply to this entry with your correction. Your assistance will be appreciated.

Thanks for reading,

Cerne 21:11, September 13, 2010 (UTC)