Welcome to Physics 12

Cell Division

Ms RitceyWelcome to Physics 12

Plan:Course outline, expectations, about me, etc.Joke of the day/clip of the day Review:SFPrecisionErrorAccuracyJoke of the day/clip of the day:Fans of the Big Bang Theory????http://www.youtube.com/watch?v=JtL5q1IACfo

MeasurementWhen taking measurements, it is important to note that no measurement can be taken exactly

Therefore, each measurement has an estimate contained in the measurement as the final digitWhen taking a measurement, the final digit is an estimate and an error estimate should be included

Least CountWhen using a measuring device (non-digital) the least count should be determinedThe least count is the smallest division that appears on the device (i.e. for a metre stick, it would usually be mm)

When taking a measurement, the digits should be recorded one place past the least count i.e. for a metre stick, a recording should be to tenths of mmDigital DevicesDigital devices make the error estimate for you so you will simply record the digits presented on the deviceThe device should also include an error estimate in the manual or on the label of the device

Error EstimateThe error estimate should be for the final digit in a measurement and is commonly 5For a meter stick, a measurement would be recorded as 1.5743 .0005mSignificant FiguresBecause all numbers in science are based upon a measurement, the estimates contained in the numbers must be accounted forCould 1+1=3?While conventional wisdom tells us this is not true, from a science standpoint it could be:1.4+1.4=2.8Significant FiguresIt is therefore important to know when a digit is significantA digit is significant if:It is non-zero (i.e. 4246 4SFs)A zero is between two non-zeros (i.e. 40003 5SFs)A zero is to the right of the decimal and to the right of a non-zero (i.e. 4.00 3SFs or 0.00210 3SFs)All digits in scientific notation (i.e. 3.57x103 3SFs)Significant FiguresThe rule that we will use for mathematical operations and significant figures is:Consider all values used in a calculation; the one with the fewest significant figures will determine the number of significant figures in your answerPage 942 (3, 4, 5a, 5b, 6)3, 2, 3, 2, 3, 1, 3, 7, 1, 2, 4, 41.2, 2.3, 5.9, 6.9, 6.3, 4.5, 5.5, 10.9.7, 2902.5597x100, 1x103, 2.56x10-1, 5.08x10-5Precision and AccuracyPrecision describes the exactness and repeatability of a value or set of values. A set of data could be grouped very tightly, demonstrating good precision but not necessarily accuracyAccuracy describes the degree to which the result of an experiment or calculation approximates the true value.Precision and Accuracy

ErrorRandom ErrorSmall variations due to randomly changing conditionsRepeating trials will reduce but never eliminateUnbiasedAffects precisionSystematic ErrorResults from consistent bias in observationRepeating trials will not reduceThree types: natural, instrument calibration and personalAffects accuracyThere are two types of error that need to be considered following data collection in an experiment.Error AnalysisThere are two main calculations that we will use to analyse error in an experiment

Percent DeviationMeasures accuracyPercent DifferenceMeasures precision

To do :Page 9391-5