Combining Uncertainty

Question	Answer
When combining uncertainty, the units must be.....	The same
For uncertainty of A+B or A-B, we should:	Add absolute uncertainties together then recalculate the percentage uncertainty
For uncertainty of AxB or A/B, we should:	Add the percentage uncertainty of A to the percentage uncertainty of B
For uncertainty of A^2, we should:	Double the percentage uncertainty of A
For uncertainty of A^n, we should:	Multiply the percentage uncertainty by n
For uncertainty of A x number (not measured) .....	Percentage uncertainty remains constant
For uncertainty of A / number (not measured) .....	Percentage uncertainty remains constant
If we measure the thickness of 100 sheets of paper with +/-1mm uncertainty, dividing this by 100 for the thickness of 1 sheet gives the uncertainty:	1/100 = +/-0.01mm
A circle has the radius 0.14mm. Find : 1. The area 2. The percentage uncertainty 3. the absolute uncertainty	0.14mm = 1.4x10^-4m. % uncertainty of r: 0.01/0.14 x 100 = 7.1% 1. Area = π(1.4x10^-4)^2 = 6.2x10^-8 m^2 2. % uncertainty in r^2: 7.1 x 2 = 14.2% 3. (6.2x10^-8)x14/100 = 8.69x10^-9 m^2 Therefore area = 6.2x10^-8 m^2 +/- 8.69x10^-9 m^2
How do we calculate the range?	\|Biggest - Smallest\|
When we repeat readings / judgments, the absolute uncertainty can be calculated by.....	Halving the range
When calculating the range, we should ignore.....	Anomalous results

Resource summary

	Created by Doc Boff over 6 years ago