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• 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
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 m0.01 m OR 1 cm