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## Measurements

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**1**Measurements The Metric system was developed in France during the Napoleonic reign of France in the 1790's.**“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**2**Which other countries, besides the U.S., do not use the metric system? STAT FACT According to a survey taken many years ago, the only other countries that have notofficially adopted the metric system are Liberia (in western Africa) and Myanmar (also known as Burma, in Southeast Asia).**3**Accurate Measurements • Accurate=how close the measurement is to the actual measurement. • Be sure we can compare our measurements to other people. • Scientists make repeated • measurements to increase the validity • and reliability of the results.**Accuracy vs. precision**4 Precision: When taking the same measurement over and over you get the same results. YOU CAN BE PRECISE BUT STILL BE WRONG. Accuracy: How close your results are to the TRUE/REAL results**6**• A Measurement system • must be agreed upon and • cannot change Ex: The foot.**Scale units**• Metric system attempted to do away with the confusing multiplicity of measurement scales by reducing them to a few fundamental ones.**7**Le Systeme Internationale d’Unites (SI) • 1960 • Based on Metric System**8**Standards • 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 Clip**9**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**10**Le Systeme Internationale d’Unites (SI) • English: International System of Units • Each measurement has a base unit.**11**SI System Based on multiples of ten. Examples of base units • Length • Meter • Mass • Gram • Volume • Liter • Time • Second • Temperature • -Kelvin • Energy • -Joule • Electric Current • -Ampere**Prefixes are used with the base units to indicate what**multiple of ten should be used. The most common prefixes are: Prefix- Symbol Multiple Kilo- k 1,000 Hecto- h 100 Deca- D 10 Deci- d .1 Centi- c .01 Mili- m .001 12 Prefixes BASE UNIT**Metric Conversions**• A conversion is changing the way you state the same amount! • Ex: 1 dollar • 4 quarters, 100 pennies, 10 dimes • 1meter = 100centimeters • Simply move your decimal point.**Convert the Following**• 65ml=_____L • 3948g=_____kg • 389.59m= ______km • 0.03748 mg=_____kg (use Sci. Not.) • 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**13**Laboratory Apparatuses for making Measurements**LENGTH**14 Distance**15**Length Distance Meter Stick • 1m = 100 Centimeters • 1m = 1000 millimeters 1cm = 10 mm Each line on the meter stick is a millimeter.**16**Meter Stick The last digit in all measurements is an estimate digit.**MASS**17 Amount of matter in an object**18**Triple Beam BalanceGrams 300 +70 +3.31 =373.31g**VOLUME**19 Space occupied**20**Length width Height Length x Height x Width =Volume**21**Graduated Cylinder Volume • Space an object occupies**TEMPERATURE**26 12 Kinetic Energy**27**17 TemperatureFahrenheit vs. Celsius vs. Kelvin 1742, Anders Celsius (1701-1744) Lord Kelvin (1824-1907) 1714:Daniel Gabriel Fahrenheit (1686-1736) Superfridge**29**Mass per unit Volume DENSITY**30**Derived Units Obtained by combining different units. Ex: Density Density is the amount of mass per unit volume. D = m/v**Remember...**....all measurement need a unit.**31**TYPES OF DATAQuantitative 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**Significant Figures The number of significant figures is the number of digits believed to be correct by the person doing the measuring. • For measured numbers, significant figures relate the certainty of the measurement. • As the number of significant figures increases, the more certain the measurement.**33**• 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.**34**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.**35**Examples • The significant zeroes in these measurements are colored black and the insignificant zeroes are red. • 0.0860 • 1.0030 • 0.000010203 • 18,000 • 18,000.00 • 0.10001 Want to make it easier????? Put it in Scientific Notation.**36**PracticeHow many Sig Figs? • 234.87 _____ • 38302.00 _____ • 3900.00 _____ • 0.00045 _____ • 9394000.09 _____ • 479301820 _____ • 0.00034440 _____**37**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.**38**Addition or Subtraction • Perform the operation. • Round off the result to correspond to the least precise value involved. • (fewest # of decimal places) • Example: 24.686 m + 2.343 m + 3.21 m = 30.239 m **You will report the correct calculated answer as 30.24 m.**39**Multiplication & Division Rules • Perform the operation. • Round off the result to correspond to the number with the LEAST number of significant figures. • Example: 3.22 cm x 2.1 cm = 6.762 cm2 **Reported answer: 6.8 cm2**40**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 =**41**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?**42**Temperature Conversion • Examples on Notes.**Temperature Conversion**Answers 1) -23 ºC 2) 66 ºC 3) 290 K 4) 328 K 5) 31.9 ºC 6) 230 ºF