Transcript Metric System and Conversions PPT

MEASUREMENT
The Metric System
and Conversions
Number vs. Quantity
• Quantity - number + unit
UNITS MATTER!!
The Metric System
• Easier to use because it is based on powers of 10.
• A metric unit has two parts:
A prefix and a base unit
• Example cm, mL, mg
• The prefix tells you how many times to divide or multiply
by 10
• KHD DCM
• King (kilo=1000)
Drinking (deci=1/10)
• Henry (Hecta =100)
Chocolate (centi=1/100)
• Died ( Deka =10)
Milk (Milli=1/1000)
Some Base Units
• Length - meter(m) - more than a yard
• Mass - grams(g) - about a raisin
• Volume - Liter(L) - half of a two liter bottle
Some Prefixes
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kilo
1 km = 1000 m
Hecto
1 hm = 100 m
Deka
1 dkm = 10 m
deci
1 dm = .1 m
centi
1 cm = .01 m
milli
1 mm = .001 m
Micro
1 µm = .000001 m
Nano
1 nm = .000000001 m
Dimensional Analysis
• The “Factor-Label” Method
– Units, or “labels” are
canceled, or “factored” out
g
cm ´
=
g
3
cm
3
Dimensional Analysis
• Steps:
1. Identify starting & ending
units.
2. Line up conversion factors
so units cancel.
3. Multiply all top numbers &
divide by each bottom
number.
4. Check units & answer.
Conversion Factors
• Conversion factor- a fraction based on a
definition and equal to 1
– Example:
• 1 cm = 0.01 m
• Conversion factors possible:
1 cm
0.01 m
0.01 m
OR
1 cm
Example 1
• Convert 77 kg to grams
Example 2
• Convert .0087 mL to L
Example 3
• Convert 12 yds to ft
Example 4
• Convert 32.4 cm to yards
Example 5
• Convert 50 mm to km
Example 6
• Convert 4.5 x 10-5 yr to min
Multi Dimension Conversions
• Remember……..
• 1 dimension at a time!
Example 1
• Convert 17.2 mi/hr to m/s
Example 2
• Convert 44 cm3 to in3
Example 3
• Convert 4.5 lb/ft3 to g/cm3
Questions?
• “The ultimate measure of a person is not
where they stand in moments of comfort
and convenience, but where the stand in
times of challenge and controversy.”