Sig Figs!!! Hmwk now due Friday

Notes: Significant figures - why they're important, why scientific method is used: 
Accuracy vs. precision - accuracy is how well a tool is used; an error in accuracy is caused by the user and can be corrected. precision describes the degree of measurement; is the tool measuring relatively large quantities, or is it measuring using tiny increments? When we combine measurements, we can assume that the result is only as precise as the least precise measurement that went into calculations. 
Rules for reporting significant figures: 
all nonzero digits are significant. ex: 123,456 m 
Zeroes are significant when they are between nonzero digits. 5054 L 
Zeroes are significant when they are to the R of decimal and to R of nonzero digits. 12.00m 
Zeroes are not significant when they are to the L of all nonzero digits. .000345 cm 
Zeroes are not significant when they are to the L of decimal and to R of all nonzero digits.200 m 
The last example shows a problem which arises when measuring something that comes out to an even number; if this is measured to the nearest meter, how can it be reported as such - as written, 200 could mean that the degree of precision is only the nearest 100m. 
--> Enter Scientific notation. 2.00*10^2 = 200, but the zeroes are now significant. 
We also started a practice w/s on sig figs; will finish tomorrow in class.

Tomorrow's topic:  (finishing new practice with sig figs), Our perception of time on the Earth, seasons, and Earth's Moon's phases vs. eclipses