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.

Using the Metric SystemA. 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

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 PrefixesPrefix Symbol Multiplication Factor Term

Micro u (0.000 001) one millionthMilli m (0.001) one

thousandthCenti c (0.01) one hundredthDeci d (0.1) one tenth

One Unit 1 one

Deka dk 10 tenHecto h 100 one hundredKilo k 1000 one thousandMega M 1 000 000 one million

Metric Units Used In This ClassQUANTITY 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 UnitsBase Units – independent of other units-

measureDerived Units – combination of base units-

calculated

Examples density g/L mass / volume (grams per

liter) volume m x m x m = meters cubedVelocity 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

PRACTICEConvert to Normal Convert to SN 2.3 x 1023 m 3,400,000, 3.4 x 10-5 cm .0000000456

MultiplyingCalculating in Scientific notation

Multiplying- Multiple the numbers Add the exponents

(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

AddAdd 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 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

PRACTICEAdd: 2.3 x 103 cm + 3.4 x 105 cmSubtract:  2.3 x 103 cm - 3.4 x 105 cmMultiply: : 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 unit drinking chocolate milk”

Examples1. 10.0 cm = __________m2. 34.5 mL = __________L3. 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 unitB-desired unitC-given unit A x B C B C must equal 1 use equality sheet

Equalities You Need To Know1 km = 1000 m1 m = 100 cm1 m = 1000 mm1L = 1000 mL1kg = 1000g1 g = 100cg1 g = 1000 mg

ENGLISH TO METRIC1 inch=2.5 centimeters1 gal=3.8 liters1lb= 4.4 Newtons1qt = .94 Liters1 ft = .30 meters12 in = .30 meters1 mi = 1.6 Km

Four-step approachWhen 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 min2. What are the equalities- 1 min = 60 sec3. Set up problem (bridges) 56 min 60 sec 1 min4. Solve the math problem -multiple everything on top and bottom then divide 56 x 60 / 1