Bell work: 1. If one pencil is 5.2 paper clips long, then how many paper clips is 3 pencils? 2. Re-write this number in scientific notation: 93,000,000 miles

What do we need to measure? What tools/instruments do we use to measure? Linear: length, width (distance) Area: Volume: Mass: Weight Time Temperature Ruler Micrometer Graduated cylinders Balance / scale Stop watch Thermometer Quantitative Data What units do we measure in? How do we read and record measurements properly? Universal Standard Units: Meter (length) Liter (volume) Gram (mass /weight) Celsius (temperature Use same scale (metric) NO ENGLISH UNITS! Use decimal places Accuracy and Precision Significant figures Scientific Notation Direct and Indirect measurements

Why do we need to be able to measure things? To make sense, all measurements need both . . . Why do we need to be able to measure things? Suppose we wanted to measure a 2 x 4 for building a house. Units by themselves don’t make sense. Numbers by themselves don’t make sense. A Number and a Unit! A board is meters long . . . . A board is 350 long . . . . Any Ideas?

Basic Types of Measurement Length: measures distance between objects Volume: measures the amount of space something takes up Mass: measures the amount of matter in an object In SI the basic units are: Length is the meter Mass is the gram Volume is the liter (liquid) Temperature is Celsius

Measurement System Comparisons ENGLISH SI SYSTEM LENGTH Yard / Inch Meter / Centimeter MASS Ounce / Pound Gram / Kilogram VOLUME Quart Liter TEMPERATURE Fahrenheit Celsius / Kelvin TIME Second All Measurement systems have standards. Standards are exact quantities that everyone agrees to use as a basis of comparison.

Why use the SI System? In the U.S. we use the English or Standard System, most of the rest of the world uses the Metric or SI System. Scientists use the SI System worldwide because: Measurements are easily understood by all scientists Measurements are easier to convert than the English system The SI (International System of Units) system is the measurement system used by scientists.

Map of Countries using English Units Liberia Burma

Basic Types of Measurement Length: measures distance between objects Volume: measures the amount of space something takes up Mass: measures the amount of matter in an object Other Types of measurement include: time temperature density pH

The SI System uses the following prefixes: Kilo 1000 Hecto 100 Deca 10 UNIT 1 Deci 1/10 Centi 1/100 Milli 1/1000 This system works with any SI measurement. The UNIT becomes whichever type of measurement you are making. (mass, volume, or length) It is the same system regardless if you are measuring length, mass, or volume.

centi gram It works for all types of measurement. If you’re measuring . . . Length then it is the meter (kilometer, decameter, etc.) Mass then it is the gram (centigram, milligram, etc.) Volume then it is the liter (deciliter, hectoliter, etc.) centi gram The first part of the term indicates the amount, the second part indicates the type of measurement.

How does converting units work? Unlike the English system converting in the SI System is very easy. For Example in the English system if you wanted to know how many inches in 2 miles what would you do? Take the number of miles (2). Multiply it by the number of feet in a mile (5,280). Multiply that by the number of inches in a foot (12). ANSWER: 126,720 inches in 2 miles

The SI system is much easier. For example in the metric system if you wanted to know how many centimeters were in 3 meters, what would you do? Find the unit you have (meters). Find the unit you are changing to (centimeters). Count the number of units in-between (2). Move the decimal point that many spaces, in the same direction you counted (right). 3 meters = 300 centimeters Kilo Hecto Deca UNIT Deci Centi Milli

Kilo Hecto Deca UNIT Deci Centi Milli More Conversions . . . 2,321.0 millimeters to meters = 2.321 meters 521.0 grams to hectograms = 5.21 hectograms NOTE: The digits aren’t changing, the position of the decimal is. In the English system the whole number changes! Kilo Hecto Deca UNIT Deci Centi Milli

Things to Remember All measurements need a number and a unit! Basic units of Measurement (meter, liter, gram) How to convert metric units

Precision and Accuracy Precision is a description of how close measurements are to each other. Accuracy is comparing your measurement to the actual or accepted value.

Measurement Review Measurements need a number and a unit! Basic units of Measurement (meter, liter, gram) How to convert metric units Be able to make basic measurements of volume, length, and mass Vocabulary words

State the same measurement in two different units length 10.0 in. 25.4 cm

Conversion Factors Fractions in which the numerator and denominator are EQUAL quantities expressed in different units Example: 1 in. = 2.54 cm Factors: 1 in. and 2.54 cm 2.54 cm 1 in.

Conversion factor 2.5 hr x 60 min = 150 min 1 hr cancel How many minutes are in 2.5 hours? Conversion factor 2.5 hr x 60 min = 150 min 1 hr cancel By using dimensional analysis / factor-label method, the UNITS ensure that you have the conversion right side up, and the UNITS are calculated as well as the numbers!

= 29 quarters Sample Problem You have $7.25 in your pocket in quarters. How many quarters do you have? 7.25 dollars 4 quarters 1 dollar = 29 quarters X

Kilo Hecto Deca UNIT Deci Centi Milli A rattlesnake is 2.44 m long. How long is the snake in cm? a) 2440 cm b) 244 cm c) 24.4 cm Kilo Hecto Deca UNIT Deci Centi Milli

Solution A rattlesnake is 2.44 m long. How long is the snake in cm? b) 244 cm 2.44 m x 100 cm = 244 cm 1 m

Amount of People in the World. There are 6,900,000,000 people in the world. What is a better way to write this HUGE value? Scientific Notation 6.9 X 109 People Why are we able to write the number like this?

11 11 cm 11. cm 11.0 cm 11.00 cm 101 101.0

Significant Figures – long story short, this is how well you measured something. The most confusing parts are the zeros Rules If there is a decimal point AND non-zeros before and after it, then all numbers are significant Ex: 45.65cm If the number is not greater than 1 all zeros up to the first non-zero are not significant, but everything else after that is significant. Ex: 0.00560cm If there is no decimal, any non-zero numbers are significant, as well as any zeros that are in between non-zeros. Ex: 30560cm

Sig-Fig “Box Method” Step 1 Draw a box around ALL nonzero digits, beginning with the leftmost nonzero digit and ending with the rightmost nonzero digit in the number. 0.0123012300   Step 2 If a decimal is present, draw a box around any trailing zeros. 0.01230123 00   Step 3 Consider any and all boxed digits significant. 0.01230123 00 9 sig. figs.

How many significant figures are in the following: 203.4 7600 0.000035 7600. 760.00 4 2 2 5

Bell work: 4.3 18.3 1. It takes 4.3 pencils to make a book. How many pencils does it take to make 18.3 books? _____pencils__ x ______books___ = 1 book 3.2 beans x 5 pencils = 1 pencil rug 4.3 18.3

Bellwork: 100 cm Convert 626 cm to meters: __1m____ x ________ = _______ m 2. How many significant figures in: 5280 _____ 52.80 _____ 100 cm