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. - PowerPoint PPT PresentationTRANSCRIPT
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 oneDeka 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 form7.0 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