# Orbital velocity?

1. Sep 6, 2006

### trajan22

What is the magnitude of the orbital velocity of the planet Mercury (orbit radius =5.79 * 10^{7} {km}, orbital period = 88.0 days)?

Ive been trying to solve this using this equation v=(2pi(57.9*10^9m))/(7.6*10^3)s
but it is not coming out right...the numbers in the equation are the units in meters and seconds because that must be the form of the answer. I also have to solve for accelereation and have used this equation
a=((4pi^2(57.9*10^9))/(7.6*10^6)^2
this has also not worked out and its the only equations that could even fit the problem from this particular section in the book. please help!

2. Sep 7, 2006

### andrevdh

The period is correct in the acceleration equation, but not in the velocity equation.

The acceleration is given by the velocity squared divided by the radius.