The radius of the Martian orbit around the Sun is about 4 times the radius of the orbit of Mercury. The Martian year is 687 Earth days. Then which of the following is the length of 1 year on Mercury?

Question

Vishal Gupta · Accepted Answer

A. Kepler's third law: T^2 \propto r^3. \frac{T{Mercury}}{T{Mars}} = \left(\frac{1}{4}\right)^{3/2} = \frac{1}{8}, so T{Mercury} = \frac{687}{8} \approx 86 — nearest option 88 Earth days.

Gravitation

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