Presentation on theme: "The Science of Physics Section 1-2 Holt"— Presentation transcript:
1The Science of Physics Section 1-2 Holt Measurements in Experiments
2“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
3Measurements Measurements play a BIG role in science. Measurements are taken so comparisons can be made.Measurements are used to communicate results.
4MeasurementMeasurements include a number and unit of measure. Examples?10 inches poundsUnits used in Science:Systeme International d’Unites or SI unitsModern version of metric system
5SI Units Symbol Unit Abbreviation Length meter m Mass kilogram kg Time secondsElectrical currentampereAThermodynamic temperatureKelvinKLuminous intensitycandelacdAmount of substancemolemol
6Derived UnitsDerived units are combinations of other units.Examples:
7Derived Units Derived units are combinations of other units. Examples: Speed: miles per hour or meters per second (m/s)Force: kilograms x meters / seconds2
8Meter Old Standard: 1/10,000,000 distance from equator to North Pole Current Standard: Distance light travels in a vacuum in seconds
9Kilogram Old Standard: mass of 0.001 cubic meters of water Current Standard: mass of a specificplatinum-iridium alloy cylinder
10Second 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 atomhttps://www.youtube.com/watch?v=MI9oOHrVI5M
11Length in Metric Units Centimeter-width of fingernail on your pinky Millimeter- width of a pennyMeter- distance from floorto door knob
12Mass in Metric Units Gram- 5 grams = mass of a nickel Kilogram (1000 grams) --- about 2.2 cans of beans
13Volume in Metric Units12 oz pop = 355 milliters (mL)
14Metric 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.
15Metric Units Prefixes indicating larger quantities than base unit: Kilo times biggerHecto—100 times biggerDeca---10 times biggerExamples:Kilogram (kg) —1000 grams (g)Decaliter (da) – 10 liters (L)
16Metric Units Prefixes indicating smaller quantities than base unit: deci---10 times smallercenti—100 times smallermilli times smallerExamples:centimeter (cm) —0.01 meters (m)milliliter (mL) – liters (L)
17Many more prefixesSee Table 1-3 for more prefixes used in metric system.n =µ =M =G =
18Converting 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.
19Converting 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.
20Powers of 10Numbers often expressed as powers of 10 when they are very small or very large= 3 x 10-5= 6.1 x 109
21Scientific Notation Scientific Notation: Examples: 3.2 x 10-3 9 x 107 First number is andTaken times 10 to some powerExamples:3.2 x x 107
22Homework-Refer to syllabus Quiz—You will be having a quiz soon on being able to visualize size of metric quantities.