Systems of Measurement

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Systems of Measurement

• Why do we need a standardized system of
  measurement?
• Scientific community is global
• An international language of measurement allows
  ALL scientists to communicate

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Metric System SI

• The first standardized system of measurement The
  Metric system
• Developed in France in 1795
• Named based on French word for measure
• based on powers of 10

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Components of SI

• The SI has 3 parts
• base units
• derived units
• prefixes

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SI Base Units
Physical Quantity Unit Name Symbol
length meter m
mass kilogram kg
time second s
electric current ampere A
temperature Kelvin K
amount of substance mole mol
luminous intensity candela cd
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SI Derived Units
Physical Quantity Unit Name Symbol
area square meter m2
volume cubic meter m3
speed meter per second m/s
acceleration meter per second squared m/s2
weight, force newton N
pressure pascal Pa
energy, work joule J
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Prefixes
Prefix Symbol Numerical Multiplier Exponential Multiplier
yotta Y 1,000,000,000,000,000,000,000,000 1024
zetta Z 1,000,000,000,000,000,000,000 1021
exa E 1,000,000,000,000,000,000 1018
peta P 1,000,000,000,000,000 1015
tera T 1,000,000,000,000 1012
giga G 1,000,000,000 109
mega M 1,000,000 106
kilo k 1,000 103
hecto h 100 102
deca da 10 101

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Prefixes
Prefix Symbol Numerical Multiplier Exponential Multiplier

deci d 0.1 101
centi c 0.01 102
milli m 0.001 103
micro m 0.000001 106
nano n 0.000000001 109
pico p 0.000000000001 1012
femto f 0.000000000000001 1015
atto a 0.000000000000000001 1018
zepto z 0.000000000000000000001 1021
yocto y 0.000000000000000000000001 1024
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Staircase Method
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Units of Volume

• The space occupied by matter
• Derived from length (m3)
• Non-SI Liter
• 1000 cm3 1 L 1 mL 1 cm3
• Instruments graduated cylinder, pipet, buret,
  volumetric flask

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Units of Temperature

• Temperature a measure of how hot or cold an
  object is (the avg. kinetic energy of particles
  in matter)
• Heat flows from higher temp. to lower temp.
• Why do substances expand as temp. increases?
  (exception??)

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• Celsius scale
• -freezing point of water
• -boiling point of water
• Kelvin scale, K (SI Base unit)
• -freezing point of water
• -boiling point of water
• 0 K (absolute zero)
• K C 273.15 C K 273.15

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Units of Energy

• Joule (J) SI unit of energy
• Calorie (cal)
• 1 J 0.2390 cal 1 cal 4.184 J
• How many calories are there in 75.5 J?

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Dimensional AnalysisFactor-Label Method

• Multiply by conversion factor (a fraction that
  relates the original unit and the desired unit)
• Conversion factor is always equal to 1.
• Numerator and denominator should be equivalent
  measurements.
• When measurement is multiplied by conversion
  factor, original units should cancel

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Dimensional AnalysisFactor-Label Method

• Convert 6.5 km to m

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• Convert 3.5 hours to seconds
• The speed of a skyrocket is measured and found to
  be 145.36 m/s. What is the rockets speed in
  km/h?