 # WHY DO WE USE THE METRIC SYSTEM?  Almost all other countries are using the metric system  Scientists need a universal way to communicate data (SI.

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WHY DO WE USE THE METRIC SYSTEM?  Almost all other countries are using the metric system  Scientists need a universal way to communicate data (SI Units)

THE METRIC CONVERSION CHART (STAIRCASE METHOD) Kilo 1000 units Hecto 100 units Deka 10 units Basic Unit Deci 0.1 units Centi 0.01 units Milli 0.001 units To convert to a smaller unit, move decimal point to the right or multiply. To convert to a larger unit, move decimal point to the left or divide

YouTube - metric conversions - shortcut method  Do the following conversions…  1678 mg to kg’s _____________  456 liters to ml’s ____________  6,789,000 mm’s to km’s _____________  1 liter to dl’s _____________  45 cm’s to km’s _______________

TRY THIS USING THE STAIRCASE METHOD 1000 mg = ______ g Step 1: Determine if you are going to go up or down the ladder. Step 2: Determine how many steps there are from milligrams to grams. Step 3: Move the decimal point the amount of places that was determined in steps 1 & 2.

TRY THIS USING THE STAIRCASE METHOD 1000 mg = ______ g Step 1: Determine if you are going to go up or down the ladder. Step 2: Determine how many steps there are from milligrams to grams. Step 3: Move the decimal point the amount of places that was determined in steps 1 & 2. 1

TRY THIS USING THE STAIRCASE METHOD.15 L = __________ ml

TRY THIS USING THE STAIRCASE METHOD.15 L = __________ ml 150

Scientific Notation A short-hand way of writing large numbers without writing all of the zeros.

The Distance From the Sun to the Earth 93,000,000

Step 1  Move decimal left  Leave only one number in front of decimal

Step 2  Write number without zeros

Step 3  Count how many places you moved decimal  Make that your power of ten

The power of ten is 7 because the decimal moved 7 places.

 93,000,000 --- Standard Form  9.3 x 10 7 --- Scientific Notation

Practice Problem 1) 98,500,000 = 9.85 x 10 ? 2) 64,100,000,000 = 6.41 x 10 ? 3) 279,000,000 = 2.79 x 10 ? 4) 4,200,000 = 4.2 x 10 ? Write in scientific notation. Decide the power of ten. 9.85 x 10 7 6.41 x 10 10 2.79 x 10 8 4.2 x 10 6

More Practice Problems 1) 734,000,000 = ______ x 10 8 2) 870,000,000,000 = ______x 10 11 3) 90,000,000,000 = _____ x 10 10 On these, decide where the decimal will be moved. 1)7.34 x 10 8 2) 8.7 x 10 11 3) 9 x 10 10

Complete Practice Problems 1) 50,000 2) 7,200,000 3) 802,000,000,000 Write in scientific notation. 1) 5 x 10 4 2) 7.2 x 10 6 3) 8.02 x 10 11

Scientific Notation to Standard Form Move the decimal to the right 3.4 x 10 5 in scientific notation 340,000 in standard form 3.40000 --- move the decimal

Write in Standard Form  6.27 x 10 6  9.01 x 10 4  6,270,000  90,100

Significant Figures 1.8 Any digit that is not zero is significant 1.234 kg 4 significant figures Zeros between nonzero digits are significant 606 m 3 significant figures Zeros to the left of the first nonzero digit are not significant 0.08 L 1 significant figure If a number is greater than 1, then all zeros to the right of the decimal point are significant 2.0 mg 2 significant figures If a number is less than 1, then only the zeros that are at the end and in the middle of the number are significant 0.00420 g 3 significant figures

How many significant figures are in each of the following measurements? 24 mL2 significant figures 3001 g 4 significant figures 0.0320 m 3 3 significant figures 6.4 x 10 4 molecules 2 significant figures 560 kg2 significant figures 1.8

Significant Figures 1.8 Addition or Subtraction The answer cannot have more digits to the right of the decimal point than any of the original numbers. 89.332 1.1+ 90.432 round off to 90.4 one significant figure after decimal point 3.70 -2.9133 0.7867 two significant figures after decimal point round off to 0.79 If you round off to a “5”, if the next digit is ODD, round up. If it is EVEN, round down (leave it)!

Significant Figures 1.8 Multiplication or Division The number of significant figures in the result is set by the original number that has the smallest number of significant figures 4.51 x 3.6666 = 16.536366= 16.5 3 sig figsround to 3 sig figs 6.8 ÷ 112.04 = 0.0606926 2 sig figsround to 2 sig figs = 0.061

Significant Figures 1.8 Multiplication or Division The number of significant figures in the result is set by the original number that has the smallest number of significant figures 4.51 x 3.6666 = 16.536366= 16.5 3 sig figsround to 3 sig figs 6.8 ÷ 112.04 = 0.0606926 2 sig figsround to 2 sig figs = 0.061

Accuracy – how close a measurement is to the true value Precision – how close a set of measurements are to each other accurate & precise but not accurate & not precise 1.8

1.9 Dimensional Analysis Method of Solving Problems 1.Determine which unit conversion factor(s) are needed 2.Carry units through calculation 3.If all units cancel except for the desired unit(s), then the problem was solved correctly. 1 L = 1000 mL How many mL are in 1.63 L? 1L 1000 mL 1.63 L x = 1630 mL 1L 1000 mL 1.63 L x = 0.001630 L2L2 mL

The speed of sound in air is about 343 m/s. What is this speed in miles per hour? 1 mi = 1609 m1 min = 60 s1 hour = 60 min 343 m s x 1 mi 1609 m 60 s 1 min x 60 min 1 hour x = 767 mi hour meters to miles seconds to hours 1.9

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