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norman-dorsey
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Measurement Errors
Digital scale
Addition and Subtraction Measurement Errors
baythen
bayif
Δy = the absolute error in y
Δa = the absolute error in a
Δb = the absolute error in b
?
1.07.8
1.02.5
ba
cmcmb
cmcmaExample:
cmcmba 2.09.137.82.5
Multiplication and Division Measurement Errors
c
c
b
b
a
a
y
ythen
c
abyif
cin error relative
bin error relative
ain error relative
yin error relative
c
cb
ba
a
y
y
??
05.024.4
1.07.8
1.02.5
c
ab
ggc
cmcmb
cmcmaExample:
Practice Problem: Calculate the surface area of the following rectangular prism.
8.4cm ±.1cm
4.5cm ±.1cm
3.2cm ±.1cm
Order of Magnitude – The power of ten closest to a given number.
Range of Magnitudes of the Universe
http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/
Examples:
7.0
2.0
10000
3.16
9.11 x 10-31
365
4.24 x 10-13
4,200,000
Estimate the number of heartbeats in an average human lifetime.
Estimate the volume of our body in cm3.
The mass of your backpack that contains your school materials in grams.
Fundamental of the International System (IS):
Quantity SI Unit SI Symbol
length meter m
mass kilogram kg
time second s
Electric current Ampere A
temperature Kelvin K
Matter mole mol
Luminous intensity candela cd
Random and Systematic Errors
Systematic errors push the results in the same direction. They are a system or instrument error.
Examples:A scale that has not been zeroed.A clock that runs slow or fast.Parallax error
Systematic errors present graphically as an unexpected vertical intercept or a slope which is significant different from the expected value.
Random errors are scattered about the accepted values due to variations in the performance of the instrument and operator .
Examples:Reading errorsTemperature variationsTiming errors
Random errors present graphically as scattering of data about the expected graph.
Precision and accuracy