exp 2 uncertainty Flashcards
1
Q
what is systematic error? random?
A
constant, flaw in measuring instrument
limitations in measurement or experimenter
2
Q
what is uncertainty? list some
A
range of expected values for measurement, random error 20 ml beaker +_ 5% 10ml graduated cylinder +_ 0.05 ml volumetric pipette +_ 0.04 ml analytical balance +- 0.003 ml
3
Q
how can we assess absolute certainty?
A
STD only one sigfig lowest std is most accurate ex calculation square root ( (mass 1 - mean)^2 + (mass 2 - mean)^2 + (mass 3 - mean)^2 ) /number of trials - 1 mass will be reported as mean +- std
4
Q
what is relative uncertainty?
A
relative to size of measurement, reported as a % usually
uncertainty in g / mean mass in g
5
Q
what is accuracy?
A
how close it is to true value
6
Q
what is precision?
A
how repeatable the values are
7
Q
how is m (slope) found?
A
m= y1-y2/x1-x2
8
Q
what does each variable im y=mx + b represent for this lab?
A
y=mass
m=slope, density
x=volume
b=y intercept, should be 0
9
Q
how do we calculate mean density?
A
add all densities, divide by number of measurements
