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Measurements The Metric system was developed in France during the Napoleonic reign of France in the 1790's. 1
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“Weights and measures may be ranked among the necessaries of life to every individual of human society…They are necessary to every occupation of human industry.... The knowledge of them, as in established use, is among the first elements of education...” JOHN QUINCY ADAMS - Report to the Congress, 1821
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Which other countries, besides the U.S., do not use the metric system? According to a survey taken many years ago, the only other countries that have not officially adopted the metric system are Liberia (in western Africa) and Myanmar (also known as Burma, in Southeast Asia). STAT FACT 2
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Accurate Measurements Be sure we can compare our measurements to other people. Scientists make repeated measurements to increase the validity and reliability of the results. 3 Accurate=how close the measurement is to the actual measurement.
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Accuracy vs. precision Precision: When taking the same measurement over and over you get the same results. Accuracy: How close your results are to the TRUE/REAL results Y O U C A N B E P R E C I S E B U T S T I L L B E W R O N G. 4
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A Measurement system 1.must be agreed upon and 2.cannot change Ex: The foot. 6
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Scale units Metric system attempted to do away with the confusing multiplicity of measurement scales by reducing them to a few fundamental ones.
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Le Systeme Internationale d’Unites (SI) 1960 Based on Metric System 7
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Standards Standards are exact quantity that people agree to use for a certain measurement. –Ex: The meter –The speed that light travels in a vacuum 1/299 792 458 of a second. –Why….This seems CRAZY!!! –The meter ClipThe meter 8
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Another Example of a Standard …..The kilogram The official kilogram, made of platinum-iridium, remains in France at the International Bureau of Weights and Measures Clip 9
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Le Systeme Internationale d’Unites (SI) English: International System of Units Each measurement has a base unit. 10
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SI System Based on multiples of ten. Examples of base units Length –Meter Mass –Gram Volume –Liter Time –Second 11 Temperature -Kelvin Energy -Joule Electric Current -Ampere
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Prefixes Prefixes are used with the base units to indicate what multiple or fraction of ten should be used.Prefixes are used with the base units to indicate what multiple or fraction of ten should be used. 12 BASE UNIT Kilo-Hecto-Deca-BUDeci-Centi-Milli- Meter Liter Gram Watt Newton Second Joule khDdcm Based on Multiples of TEN Multiple of BUFraction of BU King Henry Died Drinking Choc. Milk 1000x 100x10x 0.10.01 0.001 1)65ml=_____L 2)3948g=_____kg 3)389.59m= ______km 4)0.03748 mg=_____kg (use Sci. Not.) 5)89304µg= _______g
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Convert the Following 1)65ml=_____L 2)3948g=_____kg 3)389.59m= ______km 4)0.03748 mg=_____kg (use Sci. Not.) 5)89304µg= _______g Scientific Notation: a method of writing, or of displaying real numbers as a decimal number between 1 and 10 followed by an integer power of 10
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Laboratory Apparatuses for making Measurement s 13
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Distance 14
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Meter Stick 1m = 100 Centimeters1m = 100 Centimeters 1m = 1000 millimeters1m = 1000 millimeters 1cm = 10 mm Length Distance 1515 Each line on the meter stick is a millimeter.
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Meter Stick 1616 The last digit in all measurements is an estimate digit.
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Amount of matter in an object 17
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Triple Beam Balance Grams 300 +70 +3.31 = 373.31g 1818
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Space occupied 19
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Length width Height Length x Height x Width =Volume 20
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Graduated Cylinder Volume Space an object occupies 2121
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Kinetic Energy 1226
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Temperature Fahrenheit vs. Celsius vs. Kelvin 1742, Anders Celsius (1701-1744) 1714:Daniel Gabriel Fahrenheit (1686- 1736) Lord Kelvin (1824-1907) Superfridge 1717 27
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Temperature Conversion Examples on Notes. K = º C + 273 º C = ( º F - 32) ÷ 1.8 º C = K - 273 º F = 1.8 ºC + 32 29
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Answers 1) -23 ºC 2) 66 ºC 3) 290 K 4) 328 K 5) 31.9 ºC 6) 230 ºF Temperature Conversion
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Mass per unit Volume 30
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Density Density: Amount of matter in a specific volume. These 2 cubes have the same VOLUME, but they have different densities. Why?
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Density practice problem Which cylinder has the greatest density? Vol: 5 ml Mass: 10g Vol: 25 ml Mass: 15 ml Density = 2 g/ml Density = 1.7 g/ml So, if I had the same amount of each cylinder (1 ml), which one would have a greater mass??
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Derived Units Obtained by combining different units. Ex: Density Density is the amount of mass per unit volume. D = m/v 31
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Remember.......all measurement need a unit.
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TYPES OF DATA Quantitative vs. Qualitative If the data collected involve observations without measurements or numbers, then it is referred to as qualitative data. Quantitative data involves numbers or measurements. 32
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Significant Figures For measured numbers, significant figures relate the certainty of the measurement. As the number of significant figures increases, the more certain the measurement. 33 The number of significant figures is the number of digits believed to be correct by the person doing the measuring.
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Your answer cannot be more accurate than the equipment used to make the measurement. The accuracy of the result is limited by the least accurate measurement. 33.2
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Sig Fig Rules Nonzero digits are always significant All final zeroes after a decimal point are significant Zeroes between two other significant digits are always significant Zeroes used solely as placeholders are NOT significant Zeroes between a decimal point and a nonzero digit are significant. 34
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Examples The significant zeroes in these measurements are colored black and the insignificant zeroes are red. 1)0.0860 2)1.0030 3)0.000010203 4)18,000 5)18,000.00 6)0.10001 Want to make it easier????? Put it in Scientific Notation. 35
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Practice How many Sig Figs? 1.234.87_____ 2.38302.00_____ 3.3900.00_____ 4.0.00045_____ 5.9394000.09_____ 6.479301820_____ 7.0.00034440_____ 36
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Arithmetic When you perform any arithmetic operation, it is important to remember that the result can never be more precise than the least precise measurement. 37
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Addition or Subtraction 1.Perform the operation. 2.Round off the result to correspond to the least precise value involved. ((fewest # of decimal places) 3.Example: 24.686 m + 2.343 m + 3.21 m = 30.239 m **You will report the correct calculated answer as 30.24 m. 38
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1.Perform the operation. 2.Round off the result to correspond to the number with the LEAST number of significant figures. 3.Example: 3.22 cm x 2.1 cm = 6.762 cm 2 **Reported answer: 6.8 cm 2 Multiplication & Division Rules 39
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Practice 1) 6.201 cm + 7.4 cm + 0.68 cm + 12.0 cm = 2) 1.6 km + 1.62 m + 1200 cm = 3) 8.264 g - 7.8 g = 4) 10.4168 m - 6.0 m = 5) 12.00 m + 15.001 m = 6) 131 cm x 2.3 cm = 7) 5.7621 m x 6.201 m = 8) 20.2 cm / 7.41 s = 9) 40.002 g / 13.000005 ml = 40
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Dimensional Analysis Problem-solving method that uses the fact that any number or expression can be multiplied by one without changing its value. Examples: –Convert 50.0 mL to liters. –How many centimeters are in 6.00 inches? –Express 24.0 cm in inches. –How many seconds are in 2.00 years? –Convert 75 g/ml into kg/L 41
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Practice 1) How many millimeters are present in 20.0 inches? 2) Convert 45.3 cm to its equivalent measurement in mm. 3) How many feet are in 2 km? 4) How many mm are in 1 mile? 5) How many µg are in 10 lb? 6) Convert 18297 cm to miles. 7) Express 17 g/ml in kg/L. 8) Change a speed of 72.4 miles per hour to its equivalent in meters per second. 9) Express 267 miles/hr in m/s 10) Convert 0.0598 mg/cm 3 to g/cm 3 42
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