Physics uncertainties

Soldato
Joined
29 Apr 2007
Posts
4,841
Location
London
I have these results

[FONT=Lucida Sans, sans-serif]Speed of Sound[/FONT]


321.0 + 6.73%
315.7 + 6.73%
333.6 + 6.73%
317.2 + 6.73%
331.8 + 6.73%
313.5 + 6.73%


When I take the mean of them what will the uncertainty be of the mean?

Thanks, Ross :D
 
Say if you have a function f of n variables x1...xn which errors associated you can work out the error in f as follows:

The error of a function is equal to the square root of the sum over i of ((df/dxi)*(the error of xi))^2 with the df/dxi being the partial derivative of f with respect to xi. If that makes sense!

Edit - I found this image which probably helps more where u(f) is the uncertainty in f.
Eqn11.gif
 
Last edited:
It just means the bigger the measurement the larger the error will be.

I'd probably take the error as 6.73% of the largest value - 6.73% of the smallest value. That should cover all posibilities.
 
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