Units of Units of MeasurementMeasurement

Understanding UnitsUnderstanding Units

Does anyone know what the high temperature is going to be Does anyone know what the high temperature is going to be today? What unit of measure do we commonly use for today? What unit of measure do we commonly use for temperature in the US. Although Fahrenheit is the unit of temperature in the US. Although Fahrenheit is the unit of measure we commonly hear, we will always use the measure we commonly hear, we will always use the International System of Units or SI. Does anyone know the SI unit International System of Units or SI. Does anyone know the SI unit of measure for temperature? (Kelvin) of measure for temperature? (Kelvin)

Units are very important. When you are completing a problem, Units are very important. When you are completing a problem, doing a lab, taking a test, it is imperative that you not only pay doing a lab, taking a test, it is imperative that you not only pay attention to the numbers, but also to the units.attention to the numbers, but also to the units.

The SI base units: mass, length, temp, etc. Then there are The SI base units: mass, length, temp, etc. Then there are derived units. The SI unit for area is (mderived units. The SI unit for area is (m22). Note that because the ). Note that because the SI unit for length is m, it follows that the area is mSI unit for length is m, it follows that the area is m22. What is the . What is the SI unit for volume? (cubic meters). Density is m/v, so kg/mSI unit for volume? (cubic meters). Density is m/v, so kg/m33 . .

The next two slides show the SI base units and derived units The next two slides show the SI base units and derived units respectively.respectively.

SI Base UnitsSI Base Units

QuantityQuantity UnitUnit SymbolSymbol

LengthLength MeterMeter mm

MassMass KilogramKilogram kgkg

TemperatureTemperature KelvinKelvin KK

TimeTime SecondSecond ss

Electric Electric CurrentCurrent

ampereampere AA

Derived UnitsDerived UnitsQuantityQuantity UnitUnit SymbolSymbol

AreaArea Square meterSquare meter mm22

VolumeVolume Cubic meterCubic meter mm33

DensityDensity Kilograms per Kilograms per cubic metercubic meter

Kg/mKg/m33

PressurePressure Pascal Pascal (kg/ms(kg/ms22))

PaPa

EnergyEnergy Joule Joule (kgm(kgm22/s/s22))

JJ

Electric Electric ChargeCharge

coulombcoulomb CC

Instruments for Instruments for MeasuringMeasuring

Metric PrefixesMetric Prefixes

We can use the prefixes as a convenient way We can use the prefixes as a convenient way to write numbers. The prefix tells us how to write numbers. The prefix tells us how many times the number is multiplied or many times the number is multiplied or divided by 10. divided by 10.

Often times we will want to convert from one Often times we will want to convert from one unit of measurement to the another. unit of measurement to the another.

Example: Height of Mt. Everest is 8848 m, Example: Height of Mt. Everest is 8848 m, how may km is this? We will need to know how may km is this? We will need to know that the prefix kilo is 1000 so 1 km = 1000 mthat the prefix kilo is 1000 so 1 km = 1000 m

8848 m x 8848 m x 1 km =1 km = 8848 km 8848 km = 8.848 km= 8.848 km

1000 m 1000 1000 m 1000

PrefixPrefix SymbolSymbol MeaningMeaning EqualityEqualitygigagiga GG Billion (10 ^9)Billion (10 ^9) 1 billion bytes = 1 billion bytes =

1 gigabyte1 gigabyte

megamega MM Million (10^ 6)Million (10^ 6) 1 million bytes 1 million bytes = 1 megabyte= 1 megabyte

kilokilo kk Thousand (10^ Thousand (10^ 3)3)

1000 meters= 1 1000 meters= 1 kilometerkilometer

decideci dd Tenth (10^ -1)Tenth (10^ -1) 1 meter = 10 1 meter = 10 decimeterdecimeter

centicenti cc Hundreth (10^ -Hundreth (10^ -2)2)

1 meter = 100 1 meter = 100 centimeterscentimeters

millimilli mm ThousandthThousandth

(10^ -3)(10^ -3)1 meter = 1000 1 meter = 1000 millimetersmillimeters

micromicro Millionth (10^ -Millionth (10^ -6)6)

1 meter = 1 meter = million million micrometersmicrometers

nanonano nn Billionth (10 ^-Billionth (10 ^-9)9)

1 meter = 1 meter = billion billion nanometersnanometers