Useful
Concepts
-
A
model
is an idealized description of a physical system that enables us to form
a conceptual framework for understanding that system.
-
There are seven SI base units or standards. The names of the base units
for mass, length, and time are kilogram, meter, and second, respectively.
-
Numbers
expressed in scientific
notation can be multiplied and divided in the following way:
 .
-
To convert from one system of units to another, first write the conversion
factor as a fraction whose numerator and denominator are physically equal
and then multiply this fraction by the quantity to be converted.
-
Numbers
arising from measurement convey the precision of the measurement by the
number of significant
figures used.
-
The
results of a calculation may not have more significant figures than is warranted
by the least precise of the values used. When multiplying or dividing, the
number of significant figures in the result is limited by the number of
significant figures in the least-precise value. When adding or subtracting
numbers, the number of decimal places in the result is the same as that
of the value with the fewest decimal places.
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