# Jupiter Ascending

Two moons of Jupiter, Callisto and Europa of masses $$m_C$$ and $$m_E$$ are orbiting in circular paths of radius $$r_C$$ and $$r_E$$ respectively about Jupiter. The radii are measured from the Jupiter’s centre of mass and the respective moons’ centre of masses.

What is the ratio of their velocities $$\dfrac{v_C}{v_E}$$ in terms of the given variables?

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