 # Using the Metric System

## Presentation on theme: "Using the Metric System"— Presentation transcript:

Using the Metric System
A. Why do scientists use the metric system? The metric system was developed in France in 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

A millimeter – There are 1,000 millimeters in a meter
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

Which measurement to USE?

Base Units (Fundamental Units)
QUANTITY NAME SYMBOL _______________________________________________ Length meter m Mass gram g Time second s Temperature Kelvin k Volume(liquid)__________liter_____________L________________

SI Prefixes Prefix Symbol Multiplication Factor Term
Micro u ( ) one millionth Milli m (0.001) one thousandth Centi c (0.01) one hundredth Deci d (0.1) one tenth One Unit one Deka dk ten Hecto h one hundred Kilo k one thousand Mega M 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 cm

Multiplying Calculating in Scientific notation
Multiple the numbers Add the exponents (2.0 x 104) (4.0 x 103) = 8.0 x 107

Dividing 9.0 x 107 3.0 x 102 3.0 x 105 divide the numbers
subtract the denominator exponent from the numerator exponent 9.0 x x 102 3.0 x 105

Add Add or subtract 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 x = 7. 0 x x = 7.3 x 104 70, ,000 = = 7.3 x104

subtract 7.0 x x = 7.0x 104 – .30 x 104 = 6.7 x 104 70, =67,000

PRACTICE Add: 2.3 x 103 cm + 3.4 x 105 cm Subtract:
Multiply: : x 103 cm X x cm Divide: : x 103 cm / x cm

Making Unit Conversions
Make conversions by moving the decimal point to the left or the right using: “ king henry died unit drinking 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
it is helpful to follow a four-step approach 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 sec 1 min 4. Solve the math problem -multiple everything on top and bottom then divide 56 x 60 / 1