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## Main Question or Discussion Point

hi,

i'm totally confused right now. i'm playing around with a simple orbital model of the sun and the earth. since my rigid body solver doesn't like the huge masses of those bodies, i just normalized the masses to those of the sun. so i have

stuff works fine so far. but of course my gravitational constant now got changed. by trying around i found that it is somewhere near

so my gravitational law looks like:

now i wanted to calculate the exact value for G_mine. and that's where i got stucked. i thought i should get the right number (maybe not the magnitude) by just using

any ideas what i'm overlooking here?

kind regards

i'm totally confused right now. i'm playing around with a simple orbital model of the sun and the earth. since my rigid body solver doesn't like the huge masses of those bodies, i just normalized the masses to those of the sun. so i have

**m_sun = 1**and**m_earth=3.0044e-6**as dimensionless numbers. also i reduced the distances to dimensionless numbers by dividing the real ones by 1 million km. so e.g. i got about**r_earth = 149**. accordingly i've divided the velocity by 1 million km to match it and multiplied it again by 1 million to speed things up. so i got a speed of about**v=29/s**(which comes from 29km/s). of course all this stuff are actually 3d vectors, i just gave you the magnitudes here for simplification.stuff works fine so far. but of course my gravitational constant now got changed. by trying around i found that it is somewhere near

**. this keeps the radius of the earth between 147 and 151.***G_mine = 132200*so my gravitational law looks like:

**F = G_mine * m1 * m2 / r²**, which in my case is about**F = 132200 * 1 * 3.0044e-6 / (149)²**now i wanted to calculate the exact value for G_mine. and that's where i got stucked. i thought i should get the right number (maybe not the magnitude) by just using

**m_earth=3.0044e-006**and maybe the actual value for G (6.674e-11). i ignored my changes to the distances, since they are multiples of 10 and even if squared they should just change the magnitude of G_mine (e.g. if i enhance the speed even more by 10, i gotta multiply G_mine by 100 because the energy is proportional to the square of the speed, which works nicely). anyway, i don't seem to be able to get where i want.any ideas what i'm overlooking here?

kind regards