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Welcome to Day 8 Aug 26 th , 2009!. SWBAT Calculate density SWBAT compute percent error of their measurements SWBAT make correct measurements Catalyst How many significant digits in 402.00ng? 300ng 0.0890ng Organize the previous three measurements according to instrument precision.
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Welcome to Day 8 Aug 26th, 2009! • SWBAT Calculate density • SWBAT compute percent error of their measurements • SWBAT make correct measurements Catalyst How many significant digits in 402.00ng? 300ng 0.0890ng Organize the previous three measurements according to instrument precision. -- If you have SCIENCE FEE MONEY turn it in -- If you have AGENDA MONEY turn it in
Agenda Day 8 • Catalyst (10min) • Density and % Error(10min) • Metric Olympics! (70min)
5 Bonus Points (next week – 1 pt off everyday) Lab Fee, Safety Contract, Notebook Set-up & Extra Item
Properties of Matter Volume The amount of space an object occupies Units for volume: milliliters (mL), liters (L), (cup, gallon)
Key Point #1: An object’s volume can be found in 4 basic ways: • Multiplying dimensions together (lwh, πr2h,4/3 πr3) • Volume displacement • Using a liquid measure (mL) • As a derived unit (D=m/v)
Key point #2: Density it the ratio of an object’s mass to its volume
Anything with a density of GREATER than 1g/mL will sink in water. Anything with a density LESS than 1g/mL will float in water.
Percent error • Key Point #3: percent error is a quantitative comparison between your value for a measurement and the true value • Tells you how far off your answer is from the true value (accuracy) • An acceptable % error for an experiment is under 5%
Percent Error %E = Vactual – Vmeasured X 100 Vactual |-------| Accuracy, Precision and % Error
Your value for water density = 0.88 Accepted value for water density = 1.0 Calculate the % error in your measurement!
Metric Olympics!!!! • You will have 10min at each station • Do not move on until I have told you to.