Ch 3: Scientific Measurement Flashcards
(41 cards)
Why is it important to be able to make measurements and decide whether a measurement is correct?
Measurements are fundamental to experimental sciences.
How are all measurements made?
By comparing what you want to know with some type of standard (measuring tool).
Measurements are not usually _____. Since they are ________, they have some ___________.
exact
estimates
uncertainty
The estimate is only as good as the _________ ____.
measuring tool
Uncertainty is communicated to imply how carefully we know the measurement. The uncertainty is in the ____ _____.
last digit
Uncertainty is stated more explicitly by using ____/_____ ________.
plus/minus notation
Scientific notation is used to _____ ____ _______ and _____ _______.
write large numbers
and
small numbers
The powers of ten in scientific notation represent the _____ _____ or _________ (order of _________).
place value
or
magnitude
order of magnitude
Scientific notation: if the power of 10 is positive, you ________ by that number of 10s.
multiply
Scientific notation: if the power of 10 is negative, you ______ by that number of 10s.
divide
To evaluate accuracy of a measurement, the measured value must be compared to the _______ _____.
correct value
To evaluate precision of a measurement, the values of two or more ________ ____________ must be compared.
repeated measurements
What is the equation for error?
Error = experimental value - accepted value
What is the equation for percent error?
Percent error = |error| / accepted value X 100%
Why must measurements always be reported to the correct number of significant figures?
Calculated answers often depend on the number of significant figures in the values used in calculation.
Rules for determining significant digits: digits from - are always significant.
1-9
Rules for determining significant digits: zeros _______ ___ other significant digits are always significant (________ zeros)
between two
sandwich
Rules for determining significant digits: ___ or more additional zeros to the right of both the decimal place and another significant digit ___ significant.
one
are
Rules for determining significant digits: zeros solely used for _______ ___ _______ _____ (placeholders) are not significant.
spacing the decimal point
Rules for determining significant digits: _____ numbers or definitions of _____ have _________ or ________ number of significant figures.
exact
units
unlimited or infinite
A calculated answer cannot be more precise than the _____ precise ___________ from which it was calculated.
least
measurement
Rounding sig figs: _____ the number of significant figures in each ____ _____. Round the final answer to the _____ number of significant figures.
count
data point
least
Addition and subtraction of sig figs: the answer to an addition or subtraction problem should be rounded to the ____ number of decimal places (not ______) as the measurement with the _____ number of decimal places.
same
digits
least
Multiplication and division of sig figs: _____ the answer to the same number of significant figures as the measurement with the _____ number of significant figures.
round
least
