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Slide 2 The Science of Physics Section 1-2 Holt Measurements in Experiments Slide 3 Weights and measures may be ranked among the necessaries of life to every individual of human society. They enter into the economical arrangements and daily concerns of every family. They are necessary to every occupation of human industry; to the distribution and security of every species of property; to every transaction of trade and commerce; to the labors of the husbandman; to the ingenuity of the artificer; to the studies of the philosopher; to the researches of the antiquarian; to the navigation of the mariner, and the marches of the soldier; to all the exchanges of peace, and all the operations of war. The knowledge of them, as in established use, is among the first elements of education, and is often learned by those who learn nothing else, not even to read and write. This knowledge is riveted in the memory by the habitual application of it to the employments of men throughout life. JOHN QUINCY ADAMS - Report to the Congress, 1821 Slide 4 Measurements Measurements play a BIG role in science. Measurements are taken so comparisons can be made. Measurements are used to communicate results. Slide 5 Measurement Measurements include a number and unit of measure. Examples? 10 inches 200 pounds Units used in Science: Systeme International dUnites or SI units Modern version of metric system Slide 6 SI Units Symbol UnitAbbreviation Lengthmeterm Masskilogramkg Timeseconds Electrical currentampereA Thermodynamic temperature KelvinK Luminous intensitycandelacd Amount of substancemolemol Slide 7 Derived Units Derived units are combinations of other units. Examples: Slide 8 Derived Units Derived units are combinations of other units. Examples: Speed: miles per hour or meters per second (m/s) Force: kilograms x meters / seconds 2 Slide 9 Meter Old Standard: 1/10,000,000 distance from equator to North Pole Current Standard: Distance light travels in a vacuum in 0.0000000033 seconds Slide 10 Kilogram Old Standard: mass of 0.001 cubic meters of water Current Standard: mass of a specific platinum-iridium alloy cylinder Slide 11 Second Old Standard: 0.00001574 average solar days Current standard: 9,192,631,770 times the period of a radio wave emitted from a cesium- 133 atom https://www.youtube.com/watch?v=MI9oOHrVI5M Slide 12 Length in Metric Units Centimeter-width of fingernail on your pinky Millimeter- width of a penny Meter- distance from floor to door knob Slide 13 Mass in Metric Units Gram- 5 grams = mass of a nickel Kilogram (1000 grams) --- about 2.2 cans of beans Slide 14 Volume in Metric Units 12 oz pop = 355 milliters (mL) Slide 15 Metric Units Prefix + base unit = metric unit Prefixes are added to base units to show how much bigger or smaller the unit is. The metric system is based on powers of 10. Slide 16 Metric Units Prefixes indicating larger quantities than base unit: Kilo---1000 times bigger Hecto100 times bigger Deca---10 times bigger Examples: Kilogram (kg) 1000 grams (g) Decaliter (da) 10 liters (L) Slide 17 Metric Units Prefixes indicating smaller quantities than base unit: deci---10 times smaller centi100 times smaller milli---1000 times smaller Examples: centimeter (cm) 0.01 meters (m) milliliter (mL) 0.001 liters (L) Slide 18 Many more prefixes See Table 1-3 for more prefixes used in metric system. n = = M = G = Slide 19 Converting Metric Units Unit conversions in metric system much easier than in English system. Refer to handout. See which way to move decimal. 300 meters (m) = ________ centimeters (cm) 400 kilograms (km) = ________ grams (g) 7200 milliliters (mL) = _______ liters (L) You need to memorize prefixes from kilo to milli and be able to make these conversions without chart. Slide 20 Converting Metric Units Unit conversions in metric system much easier than in English system. Refer to handout. See which way to move decimal. 300 meters (m) = 30,000 centimeters (cm) 400 kilograms (km) = 400,000 grams (g) 7200 milliliters (mL) = 7.2 liters (L) You need to memorize prefixes from kilo to milli and be able to make these conversions without chart. Slide 21 Powers of 10 Numbers often expressed as powers of 10 when they are very small or very large 0.00003 = 3 x 10 -5 6100000000 = 6.1 x 10 9 Slide 22 Scientific Notation Scientific Notation: First number is 1 and 10 Taken times 10 to some power Examples: 3.2 x 10 -3 9 x 10 7 Slide 23 Homework-Refer to syllabus QuizYou will be having a quiz soon on being able to visualize size of metric quantities.