Calculating tau from measured time and temperature

by blairj
Tags: measured, temperature, time
blairj is offline
Mar16-09, 08:09 PM
P: 1
so i have two data points. T1 = 64.68, t1 = 200.7 and T2 = 84.15, t2 = 243. I want to use this data to find the tau value of the exponential curve the data came from.

I was trying to use simultaneous equations but got stuck. Can anyone help me with this?

64.68 = Tf(1-exp(-200.7/Tau))
84.15 = Tf(1-exp(-243/Tau))

I got to 19.47 = 84.15*(exp-200.7/Tau) - 64.68*(exp-243/Tau)

I want to get a value for Tau but i can't figure out how to simplify/remove the exponential terms.
Any help is appreciated
Phys.Org News Partner Science news on
Cougars' diverse diet helped them survive the Pleistocene mass extinction
Cyber risks can cause disruption on scale of 2008 crisis, study says
Mantis shrimp stronger than airplanes
Feldoh is offline
Mar17-09, 01:08 AM
P: 1,345
What are you trying to fit? A function of the form

[tex]f(t) = T_f(1 - exp(\frac{-t}{\tau}))[/tex]

Your best bet it to evaluate it numerically, don't think it can be analytically solved...

I get tau = -327.156 and Tf = -76.3792

Register to reply

Related Discussions
Calculating temperature change Classical Physics 2
Calculating Seal Temperature Engineering Systems & Design 2
calculating temperature using NTC thermistor Electrical Engineering 3
why are temperature/voltage/etc not measured all in KJ??? General Physics 8
What do we call the dimension measured with time? Quantum Physics 8