Circular velocity?

Question

Calculate the circular velocity of Venus and Saturn around the sun. (Hint: The mass of the sun is 2 x 1030 kg.)

Answer 1

If you don;t already have an equation for circular velocity, you can work it out by equating the centripetal force to the gravitational force...

mv^2/R = GmM/R^2

rearrange for v, and then all you need is the gravitational constant, the distance to the planet in question and mass of the sun.