1/27/09
Post date: Jan 26, 2009 9:45:35 PM
Bell Ringer: What is the main strength of the SI system?
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)
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Arithmetic with scientific notation
In order to add or subtract, we must first have common exponents for the x 10^n .
If n's are the same for each, add or subtract the M values and keep the "x 10^n" at the end
If n's are different, move the decimal in the M value until you have a common n for each, then add or subtract the M's.
To multiply
Multiply the M values to get the M for your product
Add the n values to the get the n for your product
To divide
Divide your M values to get the M for your quotient
Subtract your n values to get the n for your quotient
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Significant Figures
precision - exactness of a measurement
accuracy - how close to the actual value
sig figs show the precision of a measurement
Rules
Non-zero digits are ALWAYS significant
All final zeroes after the decimal are significant
Zeroes between other significant digits are significant
Zeroes used only for spacing the decimal are NOT significant
Example problems
251.38 --> All are non-zeroes, so 5 sig digs
1001 --> Two zeroes are between sig digs, so 4 sig digs
0.00240 --> 2 and 4 are sig., final zero after decimal is sig, other zeroes are only spacing the decimal, so 3 sig digs
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20 point quiz on Thursday
may use your notes
covers the following:
graphing, fitting a line, finding the slope
converting between units
significant figures
scientific notation