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Dimensional Analysis
What happens when you divide a number by itself?
What happens when you divide a unit by itself?
In both cases, you get the number 1. Dimensional analysis involves
multiplication and division. Focus on cancelation of UNITS Just another method of unit conversion
Conversion factors To convert between units: Figure out what CONVERSION
FACTOR you need to perform your calculation Conversion factors – take a definition and
turn it into a fraction equal to one – for example: There are 12 inches in 1 foot 12 inches or 1 foot
1 foot 12 inches
Examples of dimensional analysis
Multiply across the top. Divide by whatever’s on the bottom
Examples of dimensional analysis Convert 2.6 km to mm
First- what is the desired unit? Answer- mm
Second- how to we get from m to mm? We know that 1 km = 1000 m We know that 1 m = 1000 mm
2.6 km( 1000 m )(1000 mm) = 2600000 m
1 km 1 m
Scientific Notation
Why do we need to know this? It’s hard to work with numbers like this: 6,000,000,000,000,000,000,000 Or this 0.00000000000000000000876
What is scientific notation? Simplifying large or small numbers by
converting them to a number between 1 and 10 multiplied by powers of 10
Scientific Notation
Powers of 10? 10 x 10 x 10 = 1000 or 103
10-n = 1/10n So 10-3 = 1/103 = 1/1000 = 0.001
Converting regular notation to Scientific Notation Always move the decimal so there is
one number LEFT of the decimal If the original number is LARGER than 1
and the decimal is moved to the LEFT, use a positive exponent 1,567 = 1.567 x 103
If the original number is SMALLER than 1 and the decimal is moved to the RIGHT, use a negative exponent 0.0000045 = 4.5 x 10-6
Converting from scientific notation to regular notation Move the decimal the number of
places indicated by the exponent. If the exponent is positive, your final
number should be larger than 1 5.6 x 102 = 560
I f the exponent is negative, your final number should be smaller than 1 5.6 x 10-2 = 0.056