Uncertainty in Newton's law of cooling

In summary, the conversation is discussing the uncertainty in Newton's law of cooling, specifically in the value of k. The relevant equations are also mentioned. The uncertainty is calculated using a root-sum-square approach and the question of finding uncertainty involving logs is raised.
  • #1
sunmoonlight
8
1
Homework Statement
Uncertainty in Newton's law of cooling
Relevant Equations
T(t) = = 𝑇_𝐴+(𝑇_𝑜−𝑇_𝐴)𝑒^(−𝑘𝑡)
I'm finding the uncertainty of k, given that each temperature has an uncertainty of +/- 0.5 degress.
 
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  • #2
sunmoonlight said:
Homework Statement: Uncertainty in Newton's law of cooling
Relevant Equations: T(t) = = 𝑇_𝐴+(𝑇_𝑜−𝑇_𝐴)𝑒^(−𝑘𝑡)

I'm finding the uncertainty of k, given that each temperature has an uncertainty of +/- 0.5 degress.
You will also need approximate values for the temperatures.
Per forum rules, please show some attempt.
 
  • #3
say the T(O) = 90 +/- 0.5, T(t): 60 +/- 0.5, TA = 10 +/- 0.5, temp difference (T(t) - TA) is 50 degrees +/- 0.5, t= 100s
1. Is the uncertainty for ln (T(t) - TA) = 1/2*(ln50.5 - ln49.5) = +/-0.01?
2. If you substitute the values into the eqt, you get k = (ln50/80)/-100, so what's the uncertainty for k (like how do you find uncertainty involving logs?)
 
  • #4
sunmoonlight said:
say the T(O) = 90 +/- 0.5, T(t): 60 +/- 0.5, TA = 10 +/- 0.5, temp difference (T(t) - TA) is 50 degrees +/- 0.5, t= 100s
1. Is the uncertainty for ln (T(t) - TA) = 1/2*(ln50.5 - ln49.5) = +/-0.01?
2. If you substitute the values into the eqt, you get k = (ln50/80)/-100, so what's the uncertainty for k (like how do you find uncertainty involving logs?)
There are different concepts of uncertainty. An engineer worried about engineering tolerances would just look at the combinations of the extreme values. A scientist would take the given uncertainties as standard deviations in normal distributions and use root-sum-square approaches to combine them. I assume you are looking for the latter.

Can you find the uncertainty in ##e^{-kt}##?
 

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