Using the Metric System

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Using the Metric System. A. Why do scientists use the metric system? The metric system was developed in France in 1795 - used in all scientific work because it has been recognized as the world wide system of measurement since 1960.

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Using the Metric System

A. Why do scientists use the metric system?

• The metric system was developed in France in 1795 - used in all scientific work because it has been recognized as the world wide system of measurement since 1960.
• SI system is from the French for Le Systeme International d’Unites.
• The metric system is used in all scientific work because it is easy to use. The metric system is based upon multiples of ten. Conversions are made by simply moving the decimal point.
What is the basic unit of length?
• The meter – a little longer than a yard
What do scientists use to measure the length of an object smaller than a yard?
• A centimeter – one hundredth of a meter, so there are 100 centimeters in a meter
• A millimeter – There are 1,000 millimeters in a meter
How do scientists measure long distances?
• The kilometer – There are 1,000 meters in a kilometer
Base Units (Fundamental Units)

QUANTITY NAME SYMBOL

_______________________________________________

Length meter m

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Mass gram g

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Time second s

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Temperature Kelvin k

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Volume(liquid)__________liter_____________L________________

SI Prefixes

Prefix Symbol Multiplication Factor Term

Micro u (0.000 001) one millionth

Milli m (0.001) one thousandth

Centi c (0.01) one hundredth

Deci d (0.1) one tenth

One Unit 1 one

Hecto h 100 one hundred

Kilo k 1000 one thousand

Mega M 1 000 000 one million

Metric Units Used In This Class

QUANTITY NAME SYMBOL

Length meter m

centimeter cm

millimeter mm

kilometer km

Mass gram g

kilogram kg

centigram cg

milligram mg

Volume liter (liquid) L (l)

milliliter (liquid) mL (ml)

cubic centimeter (solid) cm3

Derived Units
• Base Units – independent of other units-measure
• Derived Units – combination of base units-calculated

Examples

• density  g/L mass / volume (grams per liter)
• volume  m x m x m = meters cubed
• Velocity  m/s (meters per second
SCIENTIFIC NOTATION
• Scientific Notation: Easy way to express very large or small numbers
• A.0 x 10x
• A – number with one non-zero digit before decimal
• x -exponent- whole number that expresses the number decimal places
• if x is (-) then it is a smaller -left
• if x is (+) than it is larger-right
PRACTICE
• Convert to Normal Convert to SN
• 2.3 x 1023 m 3,400,000,

3.4 x 10-5 cm .0000000456

Multiplying
• Calculating in Scientific notation
• Multiplying-
• Multiple the numbers
• (2.0 x 104) (4.0 x 103) = 8.0 x 107
Dividing
• divide the numbers
• subtract the denominator exponent from the numerator exponent
• 9.0 x 107 3.0 x 102
• 3.0 x 105
• get the exponents of all # to be the same
• calculate as stated
• make sure the final answer is in correct scientific notation form
• 7.0 x 10 4 + 3.0 x 10 3 =
• 7. 0 x 104 + .3 x 104 = 7.3 x 104
• 70,000 + 3,000 = 73000= 7.3 x104
subtract
• 7.0 x 10 4 - 3.0 x 10 3 =
• 7.0x 104 – .30 x 104 = 6.7 x 104
• 70,000 - 3 000 =67,000
PRACTICE
• 2.3 x 103 cm + 3.4 x 105 cm
• Subtract:
•   2.3 x 103 cm - 3.4 x 105 cm
• Multiply:
• : 2.3 x 103 cm X 3.4 x 105 cm
• Divide:
• : 2.3 x 103 cm / 3.4 x 105 cm
Making Unit Conversions
• Make conversions by moving the decimal point to the left or the right using:

“ king henry died unitdrinking chocolate milk”

Examples

• 10.0 cm = __________m
• 34.5 mL = __________L
• 28.7 mg = __________kg
Factor label method /Dimensional analysis
• Use equalities to problem solve converting units.
• quantity desired =
• quantity given x conversion factor (equality)
• A-given unit
• B-desired unit
• C-given unit
•  A x B
• C B
• C must equal 1 use equality sheet
Equalities You Need To Know

1 km = 1000 m

1 m = 100 cm

1 m = 1000 mm

1L = 1000 mL

1kg = 1000g

1 g = 100cg

1 g = 1000 mg

ENGLISH TO METRIC
• 1 inch=2.5 centimeters
• 1 gal=3.8 liters
• 1lb= 4.4 Newtons
• 1qt = .94 Liters
• 1 ft = .30 meters
• 12 in = .30 meters
• 1 mi = 1.6 Km
Four-step approach

When using the Factor-Label Method

in solving problems:

1.What is question – How many sec in 56 min

2. What are the equalities- 1 min = 60 sec

3. Set up problem (bridges) 56 min 60 sec

1 min

4. Solve the math problem -multiple everything on top

and bottom then divide 56 x 60 / 1