# Homework Help: Universal gravitation 2- determine the planet's orbital period

1. Jun 23, 2012

### dani123

1. The problem statement, all variables and given/known data

A planet's mean distance from the sun is 2.00x10^11 m. Determine the planet's orbital period. Use information found in textbook.

2. Relevant equations
So I use the following equations:

R=h+Rs

T=2∏√(R3/GxMs)

From the textbook I got the following values:

Rs=6.96x108m
ms=1.99x1030kg

3. The attempt at a solution

From the problem we also know that h=2x1011m

So with that and the radius of the sun we are able to find the radius that will be used in the orbital period equation. R=(6.96x108m)+(2x1011m)=2.007x1011m

with all these values we plug them into the orbital period equation and solve for T=49034131.61

I don't know how to get the units for the period however... If someone could tell me if my calculations are correct and how I find these units that would be greatly appreciated! Thank you so much in advance for your time and help!

2. Jun 23, 2012

### HallsofIvy

Since you just wrote numerical values for "R", "Rs", h, and "Ms" without saying what any of those mean I don't see how anyone can determine what you are doing much less what the units should be.