if I have the velocity of the planetary orbit and the mass of the sun, how do I get the radius of the orbit? I have v=root GM/r or

velocity of 2x10^4 m/s = root of 6.67x10^-11 x 2 x 10^30 kg over the radius. I am learning math all over since I retired so I can enjoy astrophysics

jwveverkahotmailcom
Aug 20, 2015

#2**+5 **

You know jwveverka you probably not have to learn maths all over. The maths on Earth is the same as the maths in outer space.

Maybe maths is different in Brazil though

Dragonlance
Aug 20, 2015

#1**+5 **

v = √(G*M/r) can be rewritten as v^{2} = G*M/r, which can then be rearranged as r = G*M/v^{2}

$${\mathtt{r}} = {\frac{{\mathtt{6.67}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{\left(-{\mathtt{11}}\right)}{\mathtt{\,\times\,}}{\mathtt{2}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{\left({\mathtt{30}}\right)}}{{\left({\mathtt{2}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{{\mathtt{4}}}\right)}^{{\mathtt{2}}}}} \Rightarrow {\mathtt{r}} = {\mathtt{333\,500\,000\,000}}$$

r = 3.335*10^{11} m

.

Alan
Aug 20, 2015

#2**+5 **

Best Answer

You know jwveverka you probably not have to learn maths all over. The maths on Earth is the same as the maths in outer space.

Maybe maths is different in Brazil though

Dragonlance
Aug 20, 2015