# Homework Help: Calculating the orbital Velocity and orbital period.

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1. Apr 6, 2015

1. The problem statement, all variables and given/known data
Find the orbital velocity of the satellite 300km above the MARS surface.
Mass of mars: M = 6.419 x 1026kg
Gravitational constant: G = 6.674 x 10-11m3/kg/s2

2. Relevant equations
Vc2 = GM1/R

3. The attempt at a solution
I've already posted once, but need more help. If one of the threads must be deleted, please delete the earlier one.
I don't know how to put this into a calculator to get the answer I need, because I don't understand how to interpret the many units of measurement after the G constant. After combining the radius with the orbit distance, and thereafter plugging the equation and taking the result's square root -
My current answer is 11591.0189394, which I take to mean "11.591" km/s, which must be incorrect.
Thanks.

2. Apr 6, 2015

### SteamKing

Staff Emeritus
First, the mass of Mars listed in you problem statement is incorrect. The mass of Mars is 1/1000 of the value listed.

http://en.wikipedia.org/wiki/Mars

It's not clear what you are talking about here.

Calculators are used to crunch numbers, not units. You can do a separate reconciliation of the units to determine if you get the units of velocity (m/s). Remember to use consistent units for the values of R, M, and G in your calculations. If G has units of kg, m, and seconds, then M must have units of kg, and R must have units of meters.

Use the correct value for the mass of Mars and calculate the orbital velocity.