Root mean square velocity of CO2 molecules

[Plasma]

Homework Statement

If the translationa speed of the water vapor molecules (H2O) in ir is 648 m/s, what is the translational rms speed of the carbon dioxide molecules in the same air? Both gases are at the same tmperature.

Homework Equations

V^2 = (3kT)/m

The Attempt at a Solution

I'm not even sure where to begin. I don't understand how knowing the water's speed helps me find the CO2's.

 

[Astronuc]

A good reference.
http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/kintem.html#c2

But knowing that V^2 = (3kT)/m and that the H₂O and CO₂ have the same temperature T, what can one say about V²/m for each molecule?

 

[Plasma]

They must be the same.