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Uncertainty•All measurements have a degree of unreliability
•Usually in the last digit of a measurement
0
1
2
3
BuretteMeasurements
Eachmeasurementshould have2 decimals
Solve thecorrectreading for thevolumein theburette
0
1
2
3
BuretteMeasurements
Eachmeasurementshould have2 decimals
~ 1.36
the lastdecimalwill haveuncertainty
Determining Significance
• All non-zero digits
• All zeros between non-zero numbers
• All trailing zeros if there is a decimal place
Multiplication Uncertainty
• The answer should have the same number of significant digits as the multiplier with the least number of SD
• Same for division
Addition Uncertainty• When adding, line up decimal
place & add
• The decimal places in the answer should = the least
• Same for subtraction
Conversion Factor• Ratio equal to one
• 12 inches/1 foot = 1
• Multiply one unit by a CF to obtain another unit w/o affecting magnitude
Calculate the mass in kg of a board that has
dimensions of 250 mm x 4.0 x 104 m x 2.5 m and
had a density of 0.80 g/mL1 ml = 1 cm3
Calculate the density in g/mL of a 3.14 x 103 kg cylinder that 5.0 m long & has a diameter of 2.0 m.
Determine the length in miles of a light year
• Light year = distance light travels in one year
• c = 3.0 x 108 m/s
• 1 mile = 5280 ft
• 1 inch = 2.54 cm