Presentation on theme: "SI (Système International d’unités)"— Presentation transcript:
1SI (Système International d’unités) Metric System
2Introduction The thermometer says 39°C. Your school is 2 km away. Do you need a warm jacket or your shortsYour school is 2 km away.Do you need a ride or can you walk?A box has a mass of 500 grams.Can you lift this by yourself or do you need help?Milk comes in a 2 liter container.Can you share with your friends, or do you only have enough for yourself?
3Measurement HistorySince the beginning of time people have been measuringEarliest recorded measurements involved lengthEgypt, 3000 BCCubitPalmDigit
4Length History Length units based on human body Hand = width of human handSpan = tip of pinky to tip of thumbFoot = human footCubit = tip of middle finger to elbowYard = tip of nose to thumbFathom = finger tip – finger tip of outstretched armsMile = “mille passe” = 1000 double paces
5Volume History Volume originally measured by heaps or handfuls Gallon = container that held 10 pounds of waterQuarts = ¼ of gallon
6Mass History Mass originally measured by stones or seeds Grain = based on number of seedsCarat = based on “carob” seedStones = based on stonesPound = money value once based on weightEnglish still use “pound” for currencyOunce = romans divided pound into 12 units “unciae”Later divided into 16 parts
7So What’s the Problem?Problems arose with accuracy, consistency, fairnessAll feet, hands, paces aren’t the sameAll handfuls and heaps aren’t the sameDifferent countries had different measurementsGreeks divided their foot into 16 unitsRomans divided their foot into 12 unitsInch = Width of thumbEnglish used 3 barleycorns (seeds) to measure inch
8So What’s the Answer?Problems arose with accuracy, consistency, fairnessStandards were establishedStandard: Agreed upon measurements that stay the same wherever you goSystemsSystem: measurements that are all relatedCustomary System – based on bodyMetric system – based on the EarthMost widely accepted standards in world
9What is the metric system? Created in France 1793Scientists based the system on a meterMeter means “measure”Distance from equator to North Pole /10,000,000Used all over the worldUS is only major country not to useE.C. What are the only other two countries not to use metric system?Based on 10s
10Why the metric system? Scientists created and use the metric system Science occurs all over the world – not just in USAScientists need to speak the same “language” when it comes to measurementsWe’re in science classThe entire Earth (almost) uses the metric system(The United States and two others)Business and trade uses metric systemEspecially if they interact with foreign markets
11Quiz Length: Volume: How many inches in a foot How many feet in a yard?How many yards in a mile?How many inches in a mile?Volume:How many teaspoons in a tablespoon?How many tablespoons in a cup?How many cups in a gallon?
12Quiz (continued) Mass: Temperature: Extra Credit: How many ounces in a pound?How many pounds in a ton?Temperature:What is the freezing point of water?What is the boiling point of water?Extra Credit:What is a common equivalent for the following: (Choose 4)Fathom?Chain?Rod?Furlong?League?Peck?
13Extra Credit Extra Credit: What is a common equivalent for the following: (Choose 4)Fathom?Chain?Rod?Furlong?League?Peck?
14Race??? SI (Metric) Customary (American) 1.5 m 2.75 m m m1 1/2 ft 2 3/4 ft 3 1/3 ft + 4 5/8 ft
15And the Winner Is??? SI (Metric) Customary (American) m 2.75 m m m21 1/2 ft = /242 3/4 ft = /243 1/3 ft = /24/8 ft = /24(53/24 = 2 5/24) /24( /24 = /24)/24
16Easier? The metric system is easier to use than our system Only one base unit for each measurementPrefixes help with very large/small measurementsBased on 10’sDecimals not fractionsFasterVery easy to add/subtract/multiply/divideChanging prefixes; just move decimal
17Comparison SI (Metric System) Units from Earth 1 unit with prefixes Customary (American System )Units from Earth1 unit with prefixesBased on 10sDecimalsFasterUnits from bodyMany unitsBased on 2s, 3s, 4s, 8s, 12s, 16s, 36s, etc.FractionsSlowerMetric units from distance of equator to North pole / 10,000,000American units from the foot, width of finger, outstretched arms, double paces, etc.Meter, Liter, GramInches, Feet, Yards, Miles (Rod, Furlongs, Fathoms, Chains, etc.) Ounces, teaspoons, Tablespoons, Pints, Quarts, Cups, Gallons, Barrels, (hogs head, gil, dram, jigger) Ounces, Pound, Ton, (grain, dram)Everything is based on 10 – How many ____ in a ____?Inches in a foot? Feet in a yard? Feet in a mile? Yards in a mile? Ounces in a cup? Cups in a quart? Quarts in a gallon? Ounces in a pound? Pounds in a ton?Because it is based on 10s – you use decimals (tenths, hundredths, etc)American system is not based on 10s and we usually use fractions, 17/64, ½, ¼, etcBecause you use decimals much faster – race (
25Length Summary Length: distance between two points Instrument: metric ruler / meter stickBase unit: meter (m)Accuracy:Start at the “0”Count accuratelyMeter sticks end to endMeasure in a straight line
26Volume Summary Volume: amount of space an object takes up Instrument: graduated cylinderBase unit: liter (L)1 cm3 = 1 mLAccuracy:Know what you are counting by 0.5s, 1’s, 5s,Keep graduated cylinder on flat surfaceMeasure to bottom of meniscusRead meniscus at eye level
27Volume by Difference Measure volume of water Add object to water Easy to use numberAdd object to waterMeasure volume of water and objectSubtract beginning volume from ending volume
28Mass Summary Mass: amount of matter in an object Instrument: triple beam balanceBase unit: gram1 cm3 water = 1 mL = 1 gram1 L = 1 kgAccuracy:“Zero” triple beam balance before measuringCarefully set object on panKeep triple beam balance on flat surface
29“Zero” Triple Beam Balance Clear off panMove all riders to “0”Turn tare knob if pointer isn’t at “0”
30Mass by Difference Find mass of an object Change the object Add to itTake away from itFind the mass of the changed objectSubtract smaller mass from larger mass
31Temperature SummaryTemperature: amount of thermal (heat )energy in objectInstrument: thermometerBase unit: degree Celsius (°C)Accuracy:Know what you are counting byBelow “0” temperatures are “-”Keep thermometer in middle of substance
32Graph Summary X-axis: horizontal axis (bottom) Plot independent variableIndependent variable: variable that you change / testY-axis: vertical axis (side)Plot dependent variable onDependent variable: variable that you observe/measure
33Graph Summary (continued) Set-up your graphLabel your axes with variables and unitsLabel your axes with numbersDetermine maximum value for each variableCount number of lines across & up and downChoose an easy number to count by (1s, 2s, 5s, 10s)Label only a few of the linesPlot points (across, then up)Connect dots with line (trend line)Add title (include both variables)
34Safety Glassware: Triple beam balances: Substances: Carry with two handsSet it down carefullyKeep it in the middle of tableTriple beam balances:Keep it in the middle of the tableSubstances:Don’t eat or drink (unless given permission)