# How to find the speed of a planet around the sun

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1. Jan 13, 2016

### Matthew_Maz

1. The problem statement, all variables and given/known data
THe sun has a mass of 1.99x10*30 kg. Jupiter has a mass of 1.90x10*27 kg and a mean radius of orbit around the sun of 7.78x10*8 km what is the speed that Jupiter travels in its orbit around the sun?

2. Relevant equations
fg=(Gm1m2)/d*2
fc=(4pie*2mr)/T*2

3. The attempt at a solution
I am not really sure how to go about solving this.. i was thinking to solve for the fg equation above, you get fg=4.17 x10*29, I am not sure if i am on the right track and some guidance would be useful. thanks

2. Jan 13, 2016

### Staff: Mentor

Assuming that Jupiter's orbit is taken to be circular, what supplies the centripetal force?
What formula involving velocity do you know for centripetal force?

By the way, make sure that your units agree when you make a calculation; Your value for fg looks to be a bit high. What are the units of G? What units did you use for d?