Uncertainty with Measurements and Working with numbers -...

1-5/1-6: UNCERTAINTY
OF MEASUREMENT &
WORKING WITH
NUMBERS

•
Uncertainty:
•
1) Measuring instruments are never completely free of
flaws.
•
2) Measuring always involves estimation.
•
Measure to the nearest increment OR 1/2 the smallest
increment.
•
Reliability:
•
precision-- gives the same result over and over
•
accuracy-- tests how close the value is to a standard

Significant Digits
•
Significant digits: the valid digits in a
measurement
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Zeros!!!
•
Nonzero integers are always significant.
•
All final zeros after the decimal point are
significant as long as there is a nonzero number
to the left of them.
•
Zeros between two other significant digits are
always significant.
•
Zeros used solely as place holders are not
significant.

Arithmetic with Significant Digits
•
Adding/Subtracting:
•
-perform the operation, and then round off