# Fractional Error and Differentiation

1. Sep 17, 2006

### Soaring Crane

The following was gathered in an experiment.

r(m)----- N1------N2-----N3----N4-------N5---N_avg---delta N
0.001---131------139---175---140-----158----148.6----15.882
0.002----90-------96---102-----87------85----92------6.228
0.003----52-------53----73-----65------55----59.6----8.139
0.004----53-------53----55-----39------54----50.8----5.946
0.005----26-------45----34 -----24------36-----33-----7.537

delta N = stand. dev. of row

The formula that describes the relationship among these variables is:

Strength of source = (4.3*10^-10)*[N(r^2)/d^2] curies, where d was found to be 0.02 m and delta r = 5*10^-5 m.

Find the error (delta s) of strength of the source.

I took the derivative of the formula:

delta s = (4.3*10^-10)/(d^2)*[(deltaN/N) + (2deltar/r)]

However, I don't know where to go from here to find /\strength.

How do I used this formula with all the individual /\N's, N_avg values, and r values?

I did do a graph of r vs. N^-1/2 and found the slope of the regression line,

where strength = (4.3*10^-10)(slope)^2/(d^2) and the line's slope is equal to Nr^2. (The value d is a constant here.)

Please I really need help. Thank you for any replies.

Last edited: Sep 17, 2006