Measuring With Scientific Units

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Measuring With Scientific Units
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MEASUREMENT

• TAKE OUT YOUR HOMEWORK
• Check your Procedure to see if you have
  measurements FOR EVERYTHING.
• BEGIN WORKING ON METRIC MANIA

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MEASUREMENT

• MEASUREMENT
• Measurement is in NUMBERS and UNITS.
• Most of the world uses the METRIC SYSTEM
• Based on the NUMBER TEN
• Based on the METER

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1.3 Measurement

• International System of Units (SI)
• MEASUREMENTS ALWAYS HAVE A NUMBER AND A UNIT
• 4m, 25s, examples??????
• Allow scientists from all over the world to
  understand one anothers measurements

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MEASUREMENT SYMBOLS
Base quantity Name Symbol
Length meter m
Mass gram g
Time seconds s
electric current Ampere A
temperature       Celsius oC
amount of substance Mole M
luminous intensity Candela Cd
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1.3 Measurement
Derived Units Derived Units  
Quantity Unit Symbol
Area square meter m²
Volume cubic meter m³
Density kilograms per cubic meter kg/m³
Pressure pascal (kg/ms²) Pa
Energy joule (kgm²/s²) J
Frequency hertz (1/s) Hz
Electric charge coulomb (As) C
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MEASUREMENT UNITS

• LENGTH
• METER measures distance
• VOLUME
• LITER Volume length x width x height cm3 or
  mL

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MEASUREMENT UNITS

• WEIGHT AND MASS
• GRAM mass weight
• WEIGHT depends on WHERE YOU ARE IN THE UNIVERSE
• Changes depend on GRAVITY
• Mass depends on THE NUMBER AND TYPE OF ATOMS
• ALWAYS STAYS THE SAME

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MEASUREMENT UNITS

• TEMPERATURE AND TIME
• CELSIUS temperature
• TEMPERATURE measures AMOUNT OF HEAT
• WHAT IS YOUR BODY TEMPERATURE?
• 98.6 F
• 37 C
• SECONDS time
• TIME measures ORDER OF EVENTS

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MEASUREMENT UNITS

• DENSITY
• GRAMS PER VOLUME density
• Density amount of MASS per unit of VOLUME
• grams / milliliter
• grams / cubic centimeter
• MASS VOLUME
• PURE WATER 1g / mL
• LEAD 11g / mL

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1.3 Measurement - PREFIXES
Prefix Symbol Factor Number Factor Word
giga G 1,000,000,000 (109) billion
mega M 1,000,000 (106) million
kilo k 1,000 (10³) thousand
hecto h 100 (10²) hundred
deca D 10 ten
Base unit m, g, L 1 meter, gram, Liter
deci d 1/10 (10 -1) tenth
centi c 1/100 (10 -2) hundredth
milli m 1/1,000 (10 -3) thousandth
micro µ 1/1,000,000 (10 -6) millionth
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CONVERSIONS

• Conversions are easy because theyre BASED ON THE
  NUMBER TEN
• Just MOVE THE DECIMAL!
• Setting up the Divisions
• k ? h ? D ? base ? d ? c ? m
• 1,000 units 100 units 10 units
  1 unit 1/10 unit
  1/100 unit 1/1,000 unit

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CONVERSIONS

• k ? h ? D ? base ? d ? c ? m
• 1,000 units 100 units 10 units
  1 unit 1/10 unit
  1/100 unit 1/1,000 unit
• If youre going from SMALL amounts to LARGE
  amounts, move the decimal TO THE LEFT
• 300 centimeters 3.00 meter
• 56 liters ______ kiloliters?
• .056 kL
• 82.3 milligrams _______ decigrams?
• .823 dg

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CONVERSIONS

• k ? h ? D ? base ? d ? c ? m
• 1,000 units 100 units 10 units
  1 unit 1/10 unit
  1/100 unit 1/1,000 unit
• If youre going from LARGE amounts to SMALL
  amounts, move the decimal TO THE RIGHT
• 95 grams 95,000 milligrams
• 20.5 decameters _________ meters?
• 205 m
• 6.82 liters .0682 cL centiliters?
• 682 cL

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CONVERSION FACTORS

• Converting from one unit to another
• You can also use a CONVERSION FACTOR a ratio
  that is equal to ONE and is used to convert from
  one unit to another
• Convert 1gram to milligrams
• 1g x 1,000mg/1g 1,000mg
• Convert 10meters to kilometers
• 10m x 1km/1,000m 0.010km

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REVIEW LENGTH

• METER distance
• Divisions
• km ? hm ? Dm ? m ? dm ? cm ? mm
• 1,000 100 10 1
  1/10 1/100 1/1,000
• Using your meter stick, show one meter, one
  decimeter, one centimeter, and one millimeter

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REVIEW VOLUME

• Volume length x width x height cm3 or
  milliliters
• Using your graduated cylinder, show one
  milliliter, one centiliter, AND one deciliter

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DENSITY

• Compare the density of the same sized objects on
  your desk.

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1.3 Measurement

• Measurements in science are DATA.
• It is important that they are both accurate and
  precise.

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1.3 Measurement

• Precision vs. Accuracy
• Precision exactness
• (more significant digits 1.256m stride, not 1m)
• Accuracy closeness to actual value.
• (using a quartz or atomic watch instead of
  counting in your head) try it.

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1.3 Measurement

• SCIENTIFIC NOTATION
• A way of expressing a value by powers of 10.
• Make very large and very small numbers easier to
  work with.
• 300,000,000
• 3.0 x 108
• .0000000088
• 8.8 x 10-9

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For practice, write these numbers out in long
form.
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