question form

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Phy 121

Your 'question form' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.

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Final Question

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Problem Number 2

A small object orbits a planet at a distance of 20000 kilometers from the center of the planet with a period of 51 minutes. What is the mass of the planet?

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This is probably a stupid question, but I cannot figure out this problem

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See also notes I included in the gradebook on the last test.

G M m / r^2 = m v^2 / r (grav. force = centrip force for a circular orbit)

Solving this form M we get

M = v^2 r / G.

G is a known universal constant and r is given. From the radius and period of the orbit you can find v.

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