- #1
Tyrannosaurus_
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Homework Statement
The planet Saturn will orbit the Sun every 19 Earth years (= 599 184 000 seconds). Assume Saturn travels on a circular orbit with a speed of 9 690m/s. What is the radius of the orbit of Saturn?
I can solve this in two different ways, and get two different values. Which is the correct approach, & why?
2. Homework Equations & attempt at solution.
T = (2πr)/V - that is, period is 2π*radius over speed.,
so, r = (T*V)/2π
so, radius = 9.24 x 1011m
However, if, the centripetal forces equals the universal law of gravitation, that is,
Fc = Fg
(m*v2)/r = (Gm1m2)/r2
r = (G*msun)/v2
r = [(6.67x10-11)(1.99x1030kg)]/(9690m/s2)
r = 1.41 x 1012m
So, why the difference? What applies, and what doesn't apply and why?
Thanks!