Planetary motion the mass of the sun

[prospec]

Homework Statement

Derive the equation using Newton's Law of gravitation and the equation for circular motion.

Homework Equations

V = \sqrt{\stackrel{GM}{r}}

Where G is the universal gravitational constant, M is the mass of the central body and r is the radius of the orbit

The Attempt at a Solution

F= GM1*m2/r2


F= GMp*Ms/r2

Fc= MpV2/r

F=FC

GMpMS/r2 = mpV2/r

I'm not sure how to derive this equation ?

 

[Janus]

Your heading in the right direction, now all you do is re-arrange the last equation until you've solved for V. (hint: some of the variables at least partially cancel out.)