Gravitational and electric fields

  • #1

Homework Statement


By considering the centripetal force which acts on a planet in a circular orbit, show that T^2 is proportional to R~^3 where T is the time taken for one orbit around the sun and R is the radius of the orbit


Homework Equations


I'm thinking keplers third law?



The Attempt at a Solution


C=2piR

P=2piR/ sqrt*GMm/r

rearranged to give P = 2pi sqrt*R^3/GM

Lost now..
 

Answers and Replies

  • #2
68
0

P=2piR/ sqrt*GMm/r


Where did that expression come from?


Find an expression for the radial acceleration in terms of the orbital speed and R.

Then use Newton's second law.
 

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