Tuesday, February 21, 2006

Relative Uncertainty

Length and Volume

What is the relative uncertainty in the following:

a) 3.26+.25m

b) The volume of a sphere with a radius r=2.86 +/- 0.08 m

a) relative uncertainty: 0.25/3.26 = 0.077 = 7.7%

b) V=4/3 pi r3

DeltaV/V=4/3 3 (Delta r) pi *r2/(4/3 pi r3)
= 3 Delta r/r

= 8.4%

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