# Maxwel distribution

1. Nov 29, 2008

### itryphysics

1. The problem statement, all variables and given/known data
A gas consisting of 15,200 molecules, each of mass 2.00×10^−26 kg , has the following distribution of speeds, which crudely mimics the Maxwell distribution:
Number of Molecules
1600
4100
4700
3100
1300
400
Speed
210
420
630
840
1050
1260

Determine Vrms for this distribution of speeds.
Given your value for Vrms , what (effective) temperature would you assign to this gas?

2. Relevant equations

Vrms = square root {Average V^2} or square root {3kT/m}

3. The attempt at a solution

So I squared all the values and then divided by the total number to obrain (Average velocity^2) and then took the square root ...the attempt failed..many thanks to anyone who helps!
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Nov 29, 2008

### Staff: Mentor

You need to first find the weighted average of the squares of the speeds.

3. Nov 29, 2008

### malawi_glenn

what do you mean by "squaring all values"?

Do you weight all speed^2 with their occurence?

4. Nov 29, 2008

### itryphysics

so the average of the squares of the speeds was 6.6885*10^5

5. Nov 29, 2008

### itryphysics

sorry for the confusion...i meant squaring all speeds..

and I dont know wht you mean by your second question :S

6. Nov 29, 2008

### malawi_glenn

then you did not do the weigted average.. look it up

7. Nov 30, 2008

### itryphysics

square root { (3kT) /m}

is that the weighted average?

8. Nov 30, 2008