# Velocity of gas

1. Sep 29, 2009

### ibysaiyan

1. The problem statement, all variables and given/known data
Calculate Velocity of an oxygen molecule at height, where the temperature is -50C.
O2 molecule: 5.4x10^-26 kg

2. Relevant equations
1/2mC^2=3/2kT

3. The attempt at a solution
=> 1/2 (5.4x10^-26) c^2 = 3/2 (1.38x10^-23) x -(50)
=> c2= 1.035x10^-21
=>c=3.21x10^-11 m/s

ermmi have a feeling that i messed somewhere lol.

2. Sep 29, 2009

### Redbelly98

Staff Emeritus
Try that step again. Also, note that you get a negative value for c2, another clue that something is wrong.

3. Sep 29, 2009

### ibysaiyan

OOhh.. i thought iT being a big negative value would be wrong..
is this what i did wrong
-1.035x10^-21/2.7x10^-26=-38.3x10^3m/s
but it cant be square root =? as its negative

Last edited: Sep 29, 2009
4. Sep 29, 2009

### Redbelly98

Staff Emeritus
That's a little better, but yes that negative is still a problem.

If I told you not to use -50 for the temperature, even though the temperature is -50 C, does that help?