Centripetal/Gravitational Force

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The discussion focuses on the gravitational and centripetal forces acting on two stars, A and B, in circular orbits around their common center of mass. The centripetal acceleration of star A is expressed as \(\frac{4\pi^2 R_a}{T^2}\). To determine the mass of star B, participants suggest equating the centripetal force on star A to the gravitational force exerted by star B. This approach clarifies the relationship between the forces and the masses involved in the system.

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  • Understanding of Newton's Law of Universal Gravitation
  • Familiarity with centripetal acceleration formulas
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  • Study the derivation of gravitational force equations, specifically \(F_g = \frac{GM_1M_2}{r^2}\)
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Orbiting Bodies Question

2. Two stars, A and B are in circular orbits of radii ra and rb, respectively, about their common center of mass at point P. Each star has the same period of revolution T.

Determine expressions for the following three quantities in terms of Ra, Rb, T, and fundamental constants.

a. The centripetal acceleration of star A
b. The mass Mb of star B


F_g=\frac{GM_1M_2}{r^2}, a_c=\frac{4pi ^2r}{T^2}



I solved for Part a and got [(4)(Ra)(pi)^2]/T^2. Part b has me stumped though. I think it has to do with the relationship between Fg and Fc and/or the fact that the periods of the two planets are equal. But when I try to solve for the mass, I keep cancelling out the mass variable. If someone could just steer me in the right direction, I would greatly appreciate it. Thanks.
 
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Equate the centripetal force on A to the force exerted on it by B.
 
Right, that makes sense... I don't know why I didn't think of that. Thanks!
 

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