measurement and si units

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Measurement and SI Measurement and SI Units Units Section 1-3 in text Section 1-3 in text

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Measurement and SI Units. Section 1-3 in text. 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 = 0.00086 meters per second. Using Scientific Notation. - PowerPoint PPT Presentation

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Page 1: Measurement and SI Units

Measurement and SI UnitsMeasurement and SI Units

Section 1-3 in textSection 1-3 in text

Page 2: Measurement and SI Units

Using Scientific NotationUsing Scientific Notation

A. Scientists often work with very A. Scientists often work with very largelarge or very or very smallsmall numbers.numbers.

1. Speed of 1. Speed of lightlight= 300,000,000 meters per second= 300,000,000 meters per second

2. Speed of 2. Speed of snailsnail = 0.00086 meters per second = 0.00086 meters per second

Page 3: Measurement and SI Units

Using Scientific NotationUsing Scientific Notation

B. B. Scientific NotationScientific Notation

1. A way of expressing a value as the 1. A way of expressing a value as the valuevalue of a number between 1 and 10 and of a number between 1 and 10 and a power of 10.a power of 10.

Page 4: Measurement and SI Units

Using Scientific NotationUsing Scientific NotationB. B. Scientific NotationScientific Notation

2. 2. Is a shortcut to writing all of the Is a shortcut to writing all of the digitsdigits in a number. in a number. a. 300,000,000 = a. 300,000,000 = 3.0 x 10 3.0 x 10 88 the the exponentexponent 8 tells you that the decimal point is 8 tells you that the decimal point is really 8 places to the really 8 places to the rightright of the 3. of the 3. b. 0.00086 = b. 0.00086 = 8.6 x 10 8.6 x 10 -4-4

1) The 1) The negativenegative exponent means the number is a exponent means the number is a decimaldecimal (small)(small)..

2) The exponent of a 4 tells you how many 2) The exponent of a 4 tells you how many decimaldecimal places there are to the places there are to the leftleft of the of the 8.6.8.6.

Page 5: Measurement and SI Units

Using Scientific NotationUsing Scientific Notation

B. B. Scientific NotationScientific Notation

3. Makes very large or very small numbers 3. Makes very large or very small numbers easiereasier to work with. to work with.

Page 6: Measurement and SI Units

Using Scientific NotationUsing Scientific Notation

C. Multiplying in Scientific NotationC. Multiplying in Scientific Notation

1. Multiply the numbers that appear 1. Multiply the numbers that appear beforebefore the the

multiplication sign.multiplication sign.

2. 2. AddAdd the exponents. the exponents.

3. Make sure answer is in 3. Make sure answer is in notation notation form.form.

D. Example of multiplying D. Example of multiplying

1. How far does light travel in 500 seconds?1. How far does light travel in 500 seconds?

(Speed of light)(time) = distance (on board)(Speed of light)(time) = distance (on board)

Page 7: Measurement and SI Units

Using Scientific NotationUsing Scientific Notation

D. Example of multiplying D. Example of multiplying 1. How far does light travel in 500 1. How far does light travel in 500 seconds?seconds? (Speed of light)(time) = distance (Speed of light)(time) = distance 300,000,000m/s X 500s = ?300,000,000m/s X 500s = ?(3.0 x 10(3.0 x 1088 m/s) X (5.0 x 10 m/s) X (5.0 x 1022 s) = s) =

15 x 1015 x 101010 m m 1.5 x 101.5 x 101111 m m

Page 8: Measurement and SI Units

Using Scientific NotationUsing Scientific Notation

**Remember number before the power of **Remember number before the power of ten must be ten must be greatergreater than1 and than1 and lessless than than 10.10.

**If you need to move the decimal to the **If you need to move the decimal to the Left; Left; ADDADD an exponent, or to the an exponent, or to the

Right; Right; SUBTRACTSUBTRACT an exponent an exponent

((LARSLARS))

Page 9: Measurement and SI Units

Using Scientific NotationUsing Scientific Notation

E. When Dividing in Scientific NotationE. When Dividing in Scientific Notation 1. Divide the numbers that appear 1. Divide the numbers that appear beforebefore the the exponentsexponents 2. 2. SubtractSubtract the exponents. the exponents.

F. Example of DividingF. Example of Dividing How long will it take for light from the sun to reach the How long will it take for light from the sun to reach the Earth? (on board)Earth? (on board) Distance ÷ velocity = time Distance ÷ velocity = time

Answer = Answer = 1.5 x 101.5 x 101111m m ÷÷ 3.0 x 10 3.0 x 1088m/s = .5 x 10m/s = .5 x 1033s = 5.0 x 10s = 5.0 x 1022ss

Page 10: Measurement and SI Units

SI Units of MeasurementSI Units of Measurement

A. For a measurement to make sense, it requires both a A. For a measurement to make sense, it requires both a numbernumber and a and a unitunit..

1. Always use measurements in numbers and 1. Always use measurements in numbers and units so that their units so that their meaningmeaning is clear. is clear.

2. Scientists use a set of measuring units called 2. Scientists use a set of measuring units called SISI, or the International System of Units., or the International System of Units.

3. By using one system of units, scientists can 3. By using one system of units, scientists can readily readily reproducereproduce one another’s one another’s measurements.measurements.

Page 11: Measurement and SI Units

SI Units of MeasurementSI Units of Measurement

B. Base units and derived unitsB. Base units and derived units

1. 1. Base UnitsBase Units- the 7 metric units on which the - the 7 metric units on which the

metric systemmetric system is based. is based.

2. 2. Derived UnitsDerived Units- are the additional units that- are the additional units that

come from come from combinations combinations of the of the basebase units. units.

3. Derived units include 3. Derived units include volumevolume (length x (length x

width x height) and width x height) and densitydensity (mass/volume). (mass/volume).

Page 12: Measurement and SI Units

SI Units of MeasurementSI Units of Measurement C. Metric PrefixesC. Metric Prefixes

1. Indicates how many times a unit should be 1. Indicates how many times a unit should be multipliedmultiplied or or divideddivided by ten. by ten. 2. 9ms = 9/1000 s = 0.009 seconds2. 9ms = 9/1000 s = 0.009 seconds 3. 12 km = 12 x 1000 m = 12,000 m3. 12 km = 12 x 1000 m = 12,000 m 4. Are used in non-metric units as well4. Are used in non-metric units as well a. a. gigabytesgigabytes= 1,000,000,000 bytes= 1,000,000,000 bytes b. b. megapixelsmegapixels = 1,000,000 pixels = 1,000,000 pixels 5. 5. conversion factorconversion factor a ratio of equivalent measurements a ratio of equivalent measurements

that that is used to is used to convertconvert a quantity expressed in one unit to a quantity expressed in one unit to

another another unit. unit.

convert from 8848 m to km (on board)convert from 8848 m to km (on board)

**notice that the meter units cancel**notice that the meter units cancel