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Post date: Jan 06, 2010 6:38:17 PM
What is scientific notation? What do we use it for?
Measurements
Are a form of observation
May provide evidence to help us formulate a theory
Accurate measurements help us make more accurate theories
The SI system (the metric system)
Used everywhere except USA and Australia
Used in SCIENCE
Uses prefixes to make larger or smaller increments
Scientific notation
Used to express very large or very small numbers
General format is M x 10^n
M is the non-zero numbers at the left side of a very large or small number. M is always a number with only one digit to the left of the decimal
n tells us how far to move the decimal place (positive means right, negative means left)
e.g. 4.5 x 10^3 is the same as 4500 (decimal in 4.5 was moved to the right 3 places)
e.g. 6.8 x 10^-3 is the same as 0.0068 (decimal in 6.8 was moved to the left 3 places)
Read "Scientific Notation" on pages 15-16
Do Page 16: 1-3 (due Wednesday), but don't turn in yet because we'll add to it
Prefixes
Each prefix has a "multiplier" associated with it. In order to change a unit with a prefix to the base unit, simply replace the prefix with the multiplier
e.g. the multiplier for kilo is 10^3, so 143 kilometers is the same as 143 x 10^3 meters.
Add Page 17: 4-5 to the previous 3 problems.
The factor-label method for changing units
See page 10 of your lab manual
Effectively, we multiply a measurement by a carefully chosen form of "1" to change the units without changing the value of the measurement.
e.g. 25.4 cm ---> inches
25.4 cm x (1 inch / 2.54 cm) = 10 inches
Homework:
Pages 16-17: 1-5
Make the following conversions, using the factor-label method:
15.3 years --> days
26 miles ---> feet
45 cm ---> inches
26.2 pounds ---> ounces