Knowing that the earth spins around the Sun for 365 days and the distance Earth->Sun is 1.5x10^11 m, what's the mass of the Sun?
F=G Me x Ms/distance^2
where Me - Mass of Earth, and Ms - Mass of Sun
In some literature, I noticed that for similar problems was used the formula for centripetal acceleration, although I'm not sure why:
acp = v^2/r=(2 x PI x r/T)^2 / r
where r - radius of Earth, and T - time for the Earth to spin around Sun (?).
The Attempt at a Solution
You can notice those two formulas. The literature I found this equation in says that F and acp are equal, but it doesn't explain why. If that's the case, then the equation will be a piece of cake. But I need to know why F (pulling force between Earth and Sun) and acp are equal (if that's correct).
THANK YOU FOR ANY HELP AT ALL!