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Laserbeam
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Homework Statement
A student working 3.0m away from you in a chemistry lab performs an experiment which creates a bad odor. It takes a while for the smell to get to you (assume air currents are negligible). You are able to move 2.0m further away from the source but the smell catches up with you in another 60s. What is the diffusion coefficient in the air for the molecules you smell?
Homework Equations
<R^2> = 6Dt
Where <R^2> is the root mean squared distance, D is the diffusion coefficient and t is time.
The Attempt at a Solution
<R^2> = 6Dt
<(3+2)^2> = 6Dt
25 = 6Dt
60s/2m = "x"s/3m
x = 90s
90s + 60s = 150s = t
25/6t = D
25/6(150) = D
D= 0.027m^2*s^-1
I can't think of another way to use the information I've been given. The answer in my back of my textbook says 0.044m^2*s^-1. I know for the root mean square distance you would add 2.0m and 3.0m and square them, but I do not know what to do for time. Or maybe I'm just going in the complete opposite direction that I should be, I have no idea.