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Chemistry and Math!
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Precision and Accuracy!
Accuracy- How close a measurement is to the accepted reference or theoretical value.
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Precision and Accuracy!
Precision - How close a measurement is to subsequent measurements
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Accuracy
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Accuracy and Precision
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Percent Error!
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Percent Error (absolute value)
| A | x = answer in % 0 = Observed value A = Actual value
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Precision and Accuracy Practice
1. Measured Mass = 3.80 g 2. Theoretical mass = 3.92 g Answer = 3.06%
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Precision and Accuracy Practice
1. Measured Mass = g 2. Theoretical mass = g Answer = 16.52
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Precision and Accuracy Practice
1. Measured Mass = 2. Theoretical mass =42.913 Answer = .09%
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Precision and Accuracy Practice
1. Measured Mass =.8696 ug 2. Theoretical mass = ug Answer = 35.35
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SI Units
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SI Units Measurement system in which different size units are related to each other by multiples of 10
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System International or SI Units
Name given to the old metric system Consists of seven base units
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(m)
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Kilogram
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Density, Volume and Mass
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Density, Volume and Mass
Density - the concentration of matter Weight - gravitational pull exerted on a substance Mass - the amount of matter Volume -the amount matter will displace or fill up a container
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Density Measurement A solid is measured in grams/cm3
A liquid is measured in grams/mL A gas is measured in grams /Liter
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Density, Volume and Mass
Volume = Mass Density Mass = (Volume) (Density) Density = Mass Volume
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Density, Volume and Mass
Volume = mL Mass = Grams Density = Grams/ml (1 ml = 1 cm3 )
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Density, Volume and Mass
Problem: 1. Density = 11.3 grams/mL 2. Mass = 51 grams 3. Volume of Displacement ? Answer = 4.51 mL
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Percent Yield Total amount of product produced in a reaction as compared to the theoretical yield. amount produced theoretical yield x 100
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Percent Yield Total amount produced is 100 grams, the theoretical yield is 125 grams. 100 grams 125 grams x 100 80% yield
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Measurement
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Instrument Precision Determined by the sensitivity of the instrument being used. Determined by the accuracy of the individual using the measurement instrument.
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Instrument Precision Platform Balance +/- 0.1 gram
Analytical Balance +/ gram 10 ml grad. cylinder +/- 0.1 ml 50 ml burette +/ ml
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Significant Digits
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Significant Digits The precision of the measurement used in chemistry.
Indicates all the numbers that are known with certainty plus one that is estimated. Example:
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Significant Digits Rules
Only apply to measurement Numbers that DO NOT apply: One dozen (counted number) Thirty kids (counted number) 12 inches = 1 foot (Definition) 60 seconds - 1 minute (Definition)
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Why Significant Digits ?
10th of a gram 1000th of a gram
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Why Significant Digits ?
100,000 kilograms 10th of a gram
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Significant Digits Rules
All nonzero digits are significant Example: (five significant digits) 22.3 (three significant digits)
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Significant Digits Rules
Zeros after the decimal point are significant Example: 32.0 (three significant digits) 2.003 (four significant digits)
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Significant Digits Rules
Zeros between nonzero digits are significant Example: 7008 (four significant digits) 1,400,002 (seven significant digits) (five significant digits)
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Significant Digits Rules
Leading zeroes or place holders are not significant. Example: (two significant digits) (four significant digits)
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Significant Digits Rules
Zeroes at the end before the decimal are not significant. Example: 25,000 (two significant digits) 13,800 (three significant digits)
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Rule Review Only apply to measurement
All nonzero digits are significant Include zeros between nonzero digits All other zeroes are significant unless they are place holders. This includes a measurement having a decimal point.
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Rule Review When determining if the zero(s) are significant or not.
Are they telling you how small the number is? (not-significant) significant digit Are they telling you that the measurement scale is for large objects? (not –significant) 155,000 – 3 significant digits
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Significant Digits Practice
9.370 grams (four significant digits) 63, grams (seven significant digits) ml (five significant digits)
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Significant Digits Practice
9,000 grams (one significant digits) grams (two significant digits) 5, ml (six significant digits)
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Significant digits in calculations
In multiplication and division the answer must contain the fewest significant figures. Example 4.38 meters x 3.1 meters = or 14 m2 2.85 cm x 7.2 cm = or 21 cm2
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Significant digits in calculations
In addition and subtraction the result must have the same number of decimal places as the one with the fewest decimal places. Example 4.38 meters meters = or 7.5 m 2.85 cm cm = or cm
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QUIZ You have conducted an experiment combining Fluorine gas with Lithium metal. The expected combination should yield 10 grams of Lithium Chloride. Determine the percent error for each of the two experiments. Determine the density of each amount given below (A or B) if the mass is correct and the displacement equals 5 mL Write out the number of significant digits for the four problems on the board A B 13 grams 17 grams 16 grams 14 grams
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Rule Review Only apply to measurement
All nonzero digits are significant Include zeros between nonzero digits All other zeroes are significant unless they are place holders. This includes a measurement having a decimal point.
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Rule Review When determining if the zero(s) are significant or not.
Are they telling you how small the number is? (not-significant) significant digit Are they telling you that the measurement scale is for large objects? (not –significant) 155,000 – 3 significant digits
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Scientific Notation
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Scientific Notation A mathematical process for writing very large numbers in an exponential factor so the number is more manageable.
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Scientific Notation A mathematical process for writing very large numbers in an exponential factor so the number is more manageable.
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Scientific Notation It is a number expressed between 1 and 10 multiplied by an exponential factor (raised to some power) Example: = 6 x 10-7 = 3.34 x 1022
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Why Scientific Notation?
Easier to read and write very large and small numbers Clearly displays the number of significant digits Easier to work with in multiplication and division
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Scientific Notation Equivalents
1 = 1.00 x 100 (all whole numbers) 10 = 1.00 x 101 100 = 1.00 x 102 1,000 = 1.00 x 103 10,000 = 1.00 x 104 100,000 = 1.00 x 105
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Scientific Notation Equivalents
.1 = 1.00 x 10-1 .01 = 1.00 x 10-2 .001 = 1.00 x 10-3 .0001 = 1.00 x 10-4 = 1.00 x 10-5
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Proper Notation Format
In chemistry ALL answers in Scientific Notation MUST be in proper notation format: One whole number Two decimal places 1.00 x 104
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Reverse Number Line
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Scientific Notation Problems!
5.30 x 10-3 Answer: 7.5 x 105 Answer: 750,000.0
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Scientific Notation Problems!
3.63 x 104 Answer: 36,300.00 32.5 x 108 Answer: 3,250,000,000.00
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Scientific Notation Problems!
0.078 Answer: 7.80 x 10-2 78,000.00 Answer: 7.80 x 104 0.0078 Answer: 7.80 x 10-3
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Reverse Number Line
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Scientific Notation in Mathematical functions
Rules of Function In addition and subtraction the exponents must be equal In multiplication the exponents are added In division the exponents are subtracted
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Scientific Notation in Mathematical functions
1.00 x x 103 1.00 x x 102 11.0 x 102 or 1.10 x 103
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Scientific Notation in Mathematical functions
1.00 x x 103 1.00 x x 102 x 102
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Scientific Notation in Mathematical functions
(1.00 x 102) x ( 1.00 x 103) (1.00 x 1.00) ( ) 1.00 x 105
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Scientific Notation in Mathematical functions
(1.00 x 102) / ( 1.00 x 103) (1.00 / 1.00) ( ) 1.00 x 10-1
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Practice
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Scientific Notation in Mathematical functions
2.00 x x 102 2.00 x x 103 Answer: x 103
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Scientific Notation in Mathematical functions
5.00 x x 103 5.00 x x 104 Answer: x 104
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Scientific Notation Problems!
(3.55 x 104 ) x (3.55 x 103 ) (3.55 x 3.55 ) x ( ) Answer: x or 1.26 x 108
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Scientific Notation Problems!
(6.22 x ) / (8.4 x 10-4 ) (6.22 / 8.4 ) ( ) Answer: 0.74 x or 7.40 x 101
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Scientific Notation Problems!
(6.22 x ) + (8.40 x 10-4 )
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Scientific Notation Problems!
(3.55 x 104 ) - (3.55 x 103 )
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Scientific Notation in Mathematical functions
(2.0 x 106) / ( 1.0 x 103)
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Scientific Notation in Mathematical functions
(3.0 x 104) x ( 1.0 x 107)
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Perform the following operations
2.00 x x 3.00 x 10-4 2.00 x 105 x 3.00 x 107 (6.22 x 102 ) / (8.41 x 104 ) (4.22 x ) / (5.42 x 10-7 ) 5.00 x x 105 3.00 x x 104 4.00 x x 104 2.00 x x 103
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Perform the following operations
3.00 x x 1.00 x 10-4 5.00 x x 7.00 x 107 (9.22 x 102 ) / (7.41 x 104 ) (8.22 x ) / (5.42 x 10-7 ) 7.00 x x 105 5.00 x x 104 5.00 x x 104 4.00 x x 103 B 3.00 x x 3.00 x 10-5 7.00 x 104 x 3.00 x 107 (9.11 x 103 ) / (7.41 x 105 ) (7.32 x ) / (2.42 x 10-6 ) 4.00 x x 105 3.00 x x 104 4.00 x x 104 2.00 x x 103
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Conversion factors
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Conversion Factors Ratio between measurements and their units
3 feet = 1 yard 1 gram = 1, mg ug - 1 mg.
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Dimensional Analysis
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Dimensional Analysis Method of managing multiple levels of conversion
Used to organize solutions to physics and chemistry problems
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Dimensional Analysis (grid system)
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Dimensional Analysis (definition)
100 cm 1 m 1 m cm
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Dimensional Analysis 2 meters = X mm 1000 mm = 1 m
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Dimensional Analysis (ratio system)
2 meters = X mm 1000 mm = 1 m x =
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Dimensional Analysis 2 mm = x Km 1000 mm = 1 m 1000 m = 1 Km
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Dimensional Analysis 1.2 x 104 mm = x Km 1.00 x 103 mm = 1 m
1.00 x 103 m = 1 Km
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Compound Calculations
Utilize derived formulas to determine the resulting calculations. Utilize dimensional analysis to determine the appropriate units
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Compound Calculations
Example What is the area of a rectangular that is 10.3m long and 3.7m wide. Provide the answer in cm2. Area = length x width 100cm = 1 m
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Dimensional Analysis Area = length x width
What is the area of a rectangular that is 10.3m long and 3.7m wide. Provide the answer in cm2. Area = length x width
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Dimensional Analysis Area = length x width
What is the area of a rectangular that is 10.3m long and 3.7m wide. Provide the answer in cm2. Area = length x width
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Dimensional Analysis Practice
Example What is the average speed of an object that travels 1856 meters in 900 seconds. Provide the answer in Kilometers. Average speed = distance / time 1000 m = 1 Km
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Average speed = distance / time
Dimensional Analysis What is the average speed of an object that travels 1856 meters in 900 seconds. Provide the answer in Kilometers. Average speed = distance / time
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Average speed = distance / time
Dimensional Analysis What is the average speed of an object that travels 1856 meters in 900 seconds. Provide the answer in Kilometers. Average speed = distance / time
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Dimensional Analysis Practice
Example What is the average acceleration of an object that travels 956 meters in 200 seconds. Provide the answer in Kilometers. Average speed = distance / time Acceleration = Average speed / time
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Dimensional Analysis Practice
What is the average acceleration of an object that travels 956 meters in 200 seconds. Provide the answer in Kilometers. 956 m Km 200 s s 1000 m
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Dimensional Analysis Practice
What is the average acceleration of an object that travels 9.56 x 102 meters in 2.00 x 102 seconds. Provide the answer in Kilometers (1.00 x 103 meters = 1 kilometer) .
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Dimensional Analysis Practice
What is the average acceleration of an object that travels 9.56 x 102 meters in 2.00 x 102 seconds. Provide the answer in Kilometers. 2.39 x Km/s2
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Complex Compound Calculations Example
A specific type of ore contains 10 grams of gold per 1000 kg. of ore. If gold is worth $400 an ounce, what mass of ore must be mined to obtain $ 1,000,000? (28.35 grams = 1 ounce)
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Dimensional Analysis Example
A specific type of ore contains 10 grams of gold per 1000 kg. of ore. If gold is worth $400 an ounce, what mass of ore must be mined to obtain $ 1,000,000? (28.35 grams = 1 ounce) $1 x oz AU g kg ore $ oz g AU
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Dimensional Analysis Example
A specific type of ore contains 10 grams of gold per 1000 kg. of ore. If gold is worth $400 an ounce, what mass of ore must be mined to obtain $ 1,000,000? (28.35 grams = 1 ounce) $1 x oz AU g kg ore $ oz g AU 7.09 x 106 kg ore
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A What is the average speed of an object that travels 2.03 x 102 meters in 1.20 x 103 seconds. Provide the answer in Kilometers. speed = dist / time 1000 meters = 1 kilometer . B What is the average speed of an object that travels 3.09 x 104 meters in 2.31 x 103 seconds. Provide the answer in Kilometers. speed = dist / time 1000 meters = 1 kilometer
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Perform the following operation using Dimensional Analysis and Scientific notation.
What is the average speed of an object that travels 2.03 x 102 meters in 1.20 x 103 seconds. Provide the answer in Kilometers. speed = dist / time 1000 meters = 1 kilometer B What is the average speed of an object that travels 3.09 x 104 meters in 2.31 x 103 seconds. Provide the answer in Kilometers. speed = dist / time 1000 meters = 1 kilometer
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End Module 2
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A B 13 grams 17 grams 14 grams 12 grams 16 grams 13 grams
QUIZ You have conducted an experiment combining Chlorine gas with Sodium metal. The expected combination should yield 15 grams of Sodium Chloride. Determine the percent error for each of your three experiments and the overall average of the total experiments conducted. A B 13 grams 17 grams 14 grams 12 grams 16 grams 13 grams
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A B 13 grams 17 grams 14 grams 12 grams 16 grams 13 grams
QUIZ You have conducted an experiment combining Chlorine gas with Sodium metal. The expected combination should yield 15 grams of Sodium Chloride. Determine the percent error for each of your three experiments and the overall average of the total experiments conducted. A B 13 grams 17 grams 14 grams 12 grams 16 grams 13 grams
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Density, Volume and Mass
Problem: 1. Density = 14.4 grams/mL 2. Mass = ? Grams 3. Volume = 6.2 mL Answer = grams
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Density, Volume and Mass
Problem: 1. Density = ? Grams/mL 2. Mass = 35 grams 3. Volume = 5.4 mL Answer = 6.48 grams/mL
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Test Review Properties of Matter Division of Matter States of Matter
Percent Error Significant Digits Scientific Notation Density Bridge Unit Analysis
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Dimensional Analysis Practice
Example What is the average acceleration of an object that travels 852 meters in 145 seconds. Provide the answer in Kilometers per minute Average speed = distance / time Acceleration = Average speed / time
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Determining Conversion Factors
Ratio and proportions 24 hours = 1 day ~ 12 hours = Y days 1 x 12 = 24 x Y 12 = 24Y Y = 12/24 Y = .5 days
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Determining Conversion Factors
Ratio and proportions 3 feet = 1 yard ~ 2 feet = Y yards 1 x 2 = 3 x Y 2 = 3Y Y = 2/3 Y = .67 yards
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