# Temperature required for new rms speed

1. Dec 4, 2011

### rubenhero

1. The problem statement, all variables and given/known data
c) Find T, the temperature at which He gas molecules have an rms speed of v = 733 m/s.

2. Relevant equations
Vrms = √(3kT/m)

3. The attempt at a solution
(Vrms2m)/3k = T
(7332*.004kg)/(3*1.381e-23J/k) = T
5.187e25k = T

Any help with figuring out what I did wrong is appreciated!

2. Dec 4, 2011

### grzz

Is not 'm' the mass of one MOELECULE of hydrogen?

3. Dec 4, 2011

### mtayab1994

You could use the following to solve if you are given the quantity of material (n):

P*V=n*R*T <=> T=(P*V)/(n*R)

For R is a constant: R=8.31

4. Dec 4, 2011

### rubenhero

Thank you grzz and mtayab1994 for responding. It would be easier if the problem did provide n to use PV = nRT. I am confused, should I be using .008 kg for the mass because helium gas has 2 atoms?

5. Dec 4, 2011

### mtayab1994

no you are fine with using .004kg

Last edited: Dec 4, 2011
6. Dec 4, 2011

### mtayab1994

By the way you can use the following as well