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Measurement. Chapter 1 Section 3 p. 14-20. Objectives. How do I use scientific notation? What are the SI units used in science? How do I convert from one unit to another? How are the Celsius, Kelvin, and F ahrenheit temperature scales alike? Different?. Scientific notation.
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Measurement Chapter 1 Section 3 p. 14-20
Objectives • How do I use scientific notation? • What are the SI units used in science? • How do I convert from one unit to another? • How are the Celsius, Kelvin, and Fahrenheit temperature scales alike? Different?
Scientific notation • Used to make very large or very small numbers easier to work with • Numbers in scientific notation look like this: 3, 650, 000 km becomes 3.65 x 106 km (Notice how many digits and where ) • Numbers greater than 1 have positive exponents • Numbers less than 1 have negative exponents 0.000 078 g becomes 7.80 x 10-5 g
Practice • Change each of the following measurements into scientific notation: • 24.8 m • 780.46 cm • 6 525 150 mg • 0.075 L • 0.000 025 kg
SI System of measurement • Universal system of measurement used by all scientists • One common system ensures that all scientists can easily understand and interpret each other’s data • SI is based on 7 metric units called base units • All other units, called derived units, are made by combining base units
Derived units • Examples of common derived units: • Area, m2 (m x m) • Volume, m3 (m x m x m) • Density, g/cm3
Measurement activity • Remeasure your paper clip, rubber band, and sheet of paper, using a centimeter ruler. Write your measurements in data table 2. • For each object, determine its length/distance in meters!
Unit conversion- you know how to do this!! • Change each of the following measurements into the units indicated: • Change 5.0 feet into yards • Change 75 s into minutes • Change 0.46 yards into inches
Converting between SI units • Prefixes representing specific values are used to convert between metric units.
To change from one unit to another, you must multiply/divide by the value of the prefixes involved • This means you have to know how the units are related, or how many of one unit equals one of another unit. • Use the prefix chart to determine which power of ten you will be using (10, 100, 1000, 1 000 000, 1 000 000 000, etc).
Determine prefix value • What is the power of ten value for each of the following? • Kilo • Centi • Micro • Answers: • 1000 • 100 • 1 000 000
Using prefix values to convert units • Conversion multiplies or divides by powers of ten to move the decimal. • Example: to change m into cm, multiply by 100. moves the decimal two places (same as number of zeros). • From small unit to large unit- divide (decimal moves left) • From large unit to small- multiply (decimal moves right)
Example • Change 245.2 mm to m • mm is smaller than m • going from small to large- dividing • milli means 1/1000 so I am working with 1000 (three zeros) • 245.2 mm = 0.2452 m 1000 mm/m
Practice • Convert each of the following: • 53.2 mm = _______ m • 85, 450 mL = __________ L • 6.88 m = _________ cm • 8 750 mm = ________km
Stair step method • Works for conversions between prefixes kilo to milli • Up the stairs- decimal left • Down the stairs- decimal right
Temperature scales • There are three common temperature scales: Celsius, Kelvin, and Fahrenheit • Each temperature scale is divided into small, equal divisions • The Fahrenheit scale has different divisions from the other scales. • The Celsius and Kelvin scales are divided the same way.
Temperature scale comparison Kelvin does not use degrees!