Measurements and Uncertainties Flashcards
How many fundamental units are in the SI System?
seven
What are the SI units?
metre, kilogram, second, ampere, kelvin, mole, candela
metre
unit of distance
kilogram
unit of mass
second
unit of time
ampere
unit of electric current
kelvin
unit of temperature
mole
one mole of substance contains as many particles as there are atoms in 12g of carbon-12
candela
unit of luminous intensity
order of magnitude
expressing a quantity as a plain power of 10
What are the two main types of uncertainty?
systematic and random
systematic error
biases in measurements in same directions (always too large or small)
result from technique used to make a measurement
random error
repeated measurements of same quantity show spread of values
include reading uncertainties
What is the uncertainty in reading an instrument?
+/- half of the smallest width of the graduations on the instument
accurate
systematic error in measurement is small
precise
random uncertainty in measurement is small
What must the value of the average period be expressed?
to same precision as the uncertainty
What do the significant figures of result reflect?
level of confidence of results
absolute uncertainty
uncertainty of result
fractional uncertainty
uncertainty of result / actual result
percentage uncertainty
uncertainty of result / actual result x100
Q = a + b, Q = a - b uncertainty
absolute uncertianty of Q = sum of absolute uncertainties of a and b
Q = ab, Q = a/b
fractional uncertainty of Q = sum of fractional uncertainties of a and b
Q = a^n, Q = nth root of a
fractional uncertainty of Q = fractional uncertainty of a x absolute value of n
