Orbital Speed The mass formula above tells you that satellites orbiting massive planets must move faster than satellites orbiting low-mass planets at the same distance. Massive planets have stronger gravity than low-mass planets so a satellite orbiting a massive planet is accelerated by a greater amount than one going around a lesser mass planet at the same distance. To balance the stronger inward gravitational pull of the massive planet, the satellite must move faster in its orbit than if it was orbiting a lesser mass planet. Of course, this also applies to planets orbiting stars, stars orbiting other stars, etc. If you solve for the orbit speed, v, in the mass formula, you can find how fast something needs to move to balance the inward pull of gravity: v 2 = (G M)/r . Taking the square root of both sides (you want just v not v 2 ), you get v = Sqrt [ (G M)/r ]. How do you do that? Find the orbital speed of Jupiter around the Sun. Jupiter's distance from the Sun is 5.2 A.U., or 7.8×10
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