Hey guys, I have a few Circular Motion and Gravitation questions that I have almost no idea how to do: 1. The orbital radius of Mars around the Sun is 1.52 times that of Earth's orbital radius (1.50 X 10^11m). In Earth years, what is the period of revolution for Mars in this orbit? (I need to know how to solve this question.) My work: 4((3.14)^2)(r)/(8.61 X 10^4)^2 = 4((3.14)^2)(1.52)/T^2 and solve for T (Sorry for the messy numbers. ) However, I have no idea if that is even close of what I should be doing. 2. Two satellites, X and Y, are placed in orbit around a planet. Satellite X has a period of revolution of 3.6 X 10^5 s and an orbital radius of 7.5 X 10^8 m. If the orbital radius of satellite Y is 3.0 X 10^9 m, what is its orbital period? I have no idea how to approach this question. 3. For gravitation and circular motion of planets and large masses, is the centripetal force equal to the gravitational force of attraction? Thank you very much guys Edit: Finally, is the period how long it takes for something to have 1 revolution, and the frequency is the number of revolutions per 1 second? Thanks again.