scien&fic measurements: length, mass, volume, and density · length, mass, volume, and density...
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Scien&ficMeasurements:Length,Mass,Volume,andDensity
SIUnitsofMeasurement• Manyoftheunitsyou’refamiliarwith(inches,feet,anddegreesFahrenheit)arenotusedinscience.
• Scien&stsuseasetofmeasuringunitscalledSI,ortheInterna&onalSystemofUnits(alsoknownasthemetricsystem)
• Whydoyouthinkweusethemetricsystem?
Measurements&Units
• Forameasurementtomakesense,itneedsanumberandaunit
BaseUnits
• Thereare7metricunits,knownasbaseunits
Length
• Themeteristhebasicunitoflengthinthemetricsystem
• 1meter=39.4inches• Tomeasurelongerdistances,youusethekilometer– Thereare1000metersinakilometer
Length(con:nued)
• Metersaredividedintocen,meters– thereare100cen&metersinameter– tomeasuresomethingsmallerthanameter,youwouldusecen&meters
• Cen,metersaredividedintomillimeters
Mass&Weight• Mass:theamountofmaQerinanobject– Ex:atruckhasmoremassthanatoycar
• Massisnotthesameasweight• Weightisyourmassmul&pliedbygravity– Yourweightisameasureofhowmuchgravityispullingyoudown
Volume• Volume:amountofspaceanobjecttakesup• Theliteristhebasicunitofvolume• Themilliliteristheunitforsmallvolumesofliquid• Thecubiccen-meter(cm3)istheunitforsmallvolumesofsolid,orliquid.
Density
• Density:themasspervolumeofanobject
MetricPrefixes
DerivedUnits
• Addi&onalSIunits,calledderivedunits,aremadefromcombina&onsofbaseunits
• Forexample:– Volume:theamountofspaceanobjecttakesup– Density:ra&oofobject’smasstoitsvolume
DerivedUnits• Specificcombina&onsofSIbaseunitsmakederivedunits.
Density• Density:themasspervolumeofanobject• DensityisacomparisonofhowmuchmaQerthereisinacertainamountofspace.
Whichoneismoredense?
Whichoneismoredense?
• Nowwhichoneismoredense?
LiquidLayers
• Ifyoupourtogetherliquidsthatdon’tmixandhavedifferentdensi&es,theywillformliquidlayers.
• TheliquidwiththehighestdensitywillbeontheboQom.
• Theliquidwiththelowestdensitywillbeonthetop.
LiquidLayers• Checkoutthispicturefromyourbook.Whichlayerhasthehighestdensity?
• Whichlayerhasthelowestdensity?• Imaginethattheliquidshavethefollowingdensi&es:– 10g/mL. 3g/mL.– 6g/mL. 5g/mL.
• Whichnumberwouldgowithwhichlayer?
LiquidLayers–Trywithyourneighbor
• Whichliquidhasthehighestdensity?
• Whichliquidhasthelowestdensity?
• Whichliquidhasthemiddledensity?