# Homework Help: Brownian Motion problem

1. Nov 17, 2006

### scarface223

In one of my hw problems it is a problem under the section of Brownian motion. It asks me to compute the average velocity of particles!

here is the exact problem:

The average speed of hydrogen molecules at 0 degrees C' is 1694 m/s. Compute the average speed of colloidal particles of "molecular weight" 3.2*10^6 g/mol.

-What I know about the problem is that the formula for avrg speed is 1.59*sqrt(kT/m), where k is the boltzmann constant! I do not understand why so much information is given? How can I convert molecular weight into simple mass? The ans is also 1.3 m/s, but i have no idea how to arrive at it, please help!! I would show more work, but I am not really getting anywhere so far

Last edited: Nov 17, 2006
2. Nov 17, 2006

### scarface223

The equipartition of energy principle requires that the KE when there is Brownian motion is 1/2kT. So if I set up the equation such that 1/2kT=1/2mv^2, am i on the right track?