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**Measurement and SI Units**

Section 1-3 in text

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**Using Scientific Notation**

A. Scientists often work with very large or very small numbers. 1. Speed of light= 300,000,000 meters per second 2. Speed of snail = meters per second

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**Using Scientific Notation**

B. Scientific Notation 1. A way of expressing a value as the value of a number between 1 and 10 and a power of 10.

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**Using Scientific Notation**

B. Scientific Notation 2. Is a shortcut to writing all of the digits in a number. a. 300,000,000 = x 10 8 the exponent 8 tells you that the decimal point is really 8 places to the right of the 3. b = 8.6 x 10 -4 1) The negative exponent means the number is a decimal (small). 2) The exponent of a 4 tells you how many decimal places there are to the left of the 8.6.

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**Using Scientific Notation**

B. Scientific Notation 3. Makes very large or very small numbers easier to work with.

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**Using Scientific Notation**

C. Multiplying in Scientific Notation 1. Multiply the numbers that appear before the multiplication sign. 2. Add the exponents. 3. Make sure answer is in notation form. D. Example of multiplying 1. How far does light travel in 500 seconds? (Speed of light)(time) = distance (on board)

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**Using Scientific Notation**

D. Example of multiplying 1. How far does light travel in 500 seconds? (Speed of light)(time) = distance 300,000,000m/s X 500s = ? (3.0 x 108 m/s) X (5.0 x 102 s) = 15 x 1010 m 1.5 x 1011 m

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**Using Scientific Notation**

**Remember number before the power of ten must be greater than1 and less than 10. **If you need to move the decimal to the Left; ADD an exponent, or to the Right; SUBTRACT an exponent (LARS)

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**Using Scientific Notation**

E. When Dividing in Scientific Notation 1. Divide the numbers that appear before the exponents 2. Subtract the exponents. F. Example of Dividing How long will it take for light from the sun to reach the Earth? (on board) Distance ÷ velocity = time Answer = 1.5 x 1011m ÷ 3.0 x 108m/s = .5 x 103s = 5.0 x 102s

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**SI Units of Measurement**

A. For a measurement to make sense, it requires both a number and a unit. 1. Always use measurements in numbers and units so that their meaning is clear. 2. Scientists use a set of measuring units called SI, or the International System of Units. 3. By using one system of units, scientists can readily reproduce one another’s measurements.

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**SI Units of Measurement**

B. Base units and derived units 1. Base Units- the 7 metric units on which the metric system is based. 2. Derived Units- are the additional units that come from combinations of the base units. 3. Derived units include volume (length x width x height) and density (mass/volume).

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**SI Units of Measurement**

C. Metric Prefixes 1. Indicates how many times a unit should be multiplied or divided by ten. 2. 9ms = 9/1000 s = seconds 3. 12 km = 12 x 1000 m = 12,000 m 4. Are used in non-metric units as well a. gigabytes= 1,000,000,000 bytes b. megapixels = 1,000,000 pixels 5. conversion factor a ratio of equivalent measurements that is used to convert a quantity expressed in one unit to another unit. convert from 8848 m to km (on board) **notice that the meter units cancel

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