 Solution

ID: past-exam-of-the-short-options-paper-of-the-physics-prelims-of-the-university-of-oxford/2019/s2/1/a/solution

P^{2} = \frac{4 π ^{2} a ^{3}}{G ( M _{1} + M _{2} )} .

Here

a

is the semimajor axis of their relative orbit,

P

G

(P / yr)^{2} = (a / AU)^{3} / [(M_{1} + M_{2}) / M_{⊙}]

, to the accuracy with which these astronomical units normalize the solar mass.

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