measurement systems and conversion procedures
DESCRIPTION
© 2010 Delmar, Cengage Learning. Objectives Interpret the systems of measurement Simplify units using dimensional analysis Perform metric system conversions Perform conversions between metric and nonmetric systems © 2010 Delmar, Cengage Learning.TRANSCRIPT
Chapter 3
Measurement Systems and Conversion Procedures
Objectives
Interpret the systems of measurement Simplify units using dimensional analysis Perform metric system conversions Perform conversions between metric and
nonmetric systems
© 2010 Delmar, Cengage Learning. 2
Objectives (cont’d.)
Perform conversions between apothecary and household systems
Perform temperature conversions between Celsius, Fahrenheit and Kelvin
© 2010 Delmar, Cengage Learning. 3
Systems of Measurement United States Customary System of
Measurement:• Distance:
– 1 ft = 12 in– 1 yd = 3 ft– 1 mi = 5280 ft
• Volume:– 8 fl oz = 1 cup– 1 pt = 2 cups– 1 qt = 2 pt– 4 qt = 1 gal
© 2010 Delmar, Cengage Learning. 4
Systems of Measurement (cont’d.) Metric system:
• m → meter → Length• l or L → liter → Volume• g → gram → Weight
– 0.91 m = 1 yd– 3.79 L = 1 gal– 28.3 g = 1 oz
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Systems of Measurement (cont’d.)
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Table 3.1 Metric Prefixes and Values
Basic Dimensional Analysis Algebraically changing or converting units
of measure• .• .
• Grams per liter
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Conversions Within the Metric Systems Horizontal format:
1. Identify decimal location in the number being converted
2. Identify prefix location on horizontal diagram3. Find the difference between the two exponents
associated with each prefix
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Conversions Within the Metric Systems (cont’d.)
Horizontal format:4. Conversion is moving right on the diagram:
– Move decimal to the right by the amount calculated in step 3
5. Conversion is moving left on the diagram:– Move the decimal to the left by the amount
calculated in step 3
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Figure 3.1 Horizontal format for metric prefixes and values
Conversions Within the Metric Systems (cont’d.)
Horizontal format: (cont’d.)• Convert 12 mL to microliters
– Identify decimal: 12.0– Identify prefixes in diagram– Difference is -3 –(-6) = 3– 12 mL = 12,000 μL
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Conversions Within the Metric Systems (cont’d.)
Dimensional analysis:• 1 will always be placed with two-letter unit
Convert: 12μL to mL• .
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Conversions Between Metric and Nonmetric
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Table 3.2 Relationships between the U.S. System and the Metric System
Conversions Between Metric and Nonmetric (cont’d.)
Convert 5 kg to oz:• Convert kg to lbs
• Convert lbs to oz
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Apothecary Systems Apothecary equivalents:
• 1 fl oz = 8 fl dr• 4 mL = 1 fl dr• 60 minims = 1 fl dr• 1 g = 15 gr• 1 gr = 60 mg• 1 mL = 16 minims• 1 pt = 16 fl oz• 1 qt = 2 pt
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Apothecary Systems (cont’d.) 50mg is how many grains?
• .
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Apothecary Systems (cont’d.) 250 fl dr equals how many milliliters?
• .
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Household Systems Household equivalents:
• 60 drops (gtt) = 1 tsp• 1 fl oz = 30 mL• 2 tbs = 1 oz• 6 fl oz = 1 teacup• 8 fl oz = 1 glass• 16 oz = 1 lb• 1 cup = 8 fl oz• 5 mL = 1 tsp
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Household Systems (cont’d.) You drank 3 ½ glasses of water
• How many ounces did you consume?• .
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Household Systems (cont’d.) How many tablespoons are in 12oz?
• .
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Household, Apothecary, and Metric Equivalents
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Temperature Conversions
Three scales to measure temperature:• Fahrenheit• Celsius• Kelvin
Converting Celsius to Fahrenheit:• . or
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Temperature Conversions (cont’d.)
0°C equals how many °F?• °F = (0° × 1.8) + 32°= 0° + 32° = 32°
75°F equals how many °C?• .
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Temperature Conversions (cont’d.)
Converting Celsius to Kelvin:• K = °C + 273.15• 100°C
K = 100° + 273.15° = 373.15°
• Converting Kelvin to Fahrenheit:• °F = 1.8K − 459.67°• 300K
°F = 1.8(300°) − 459.67° = 80.33°
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Summary To perform metric conversions, we must
be familiar with Table 3.1 Conversions within the metric system can
be done using the horizontal format Apothecary system: used in calculating
drug dosages Household system: used when
administering medications in the home
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Summary (cont’d.) The three main temperature formulas:
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