The position of a particle of mass m moving in a circular orbit with radius r = ro is given by: r(t) = ro <er>(adsbygoogle = window.adsbygoogle || []).push({});

Show using Newton's second law of motion, that if the force responsible for this motion is given by:

F = -k/r^2 <er>

a) the angular velocity is constant in time, and

b) the square of the orbital period is proportional to the cube of the orbital radius. Compute the proportionality constant.

for far part a) L = |r x mv| = |mr^2(theta dot) <ez>|

therefore theta dot = L/mr^2

how do I start part b)?

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# Homework Help: Central Forces

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