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Units of Measurement

Measurement You are making a measurement when you ¨Check you weight ¨Read your watch ¨Take your temperature ¨Weigh a cantaloupe What kinds of measurements did you make today?

Standards of Measurement When we measure, we use a measuring tool to compare some dimension of an object to a standard.

Some Tools for Measurement

Learning Check From the previous slide, state the tool (s) you would use to measure A. temperature __________ B. volume ____________________ C. time __________ D. weight __________

Solution From the previous slide, state the tool (s) you would use to measure A. temperature thermometer B. volume measuring cup, graduated cylinder C. time watch D. weight scale

Learning Check What are some U. S. units that are used to measure each of the following? A. length B. volume C. weight D. temperature

Solution Some possible answers are A. length inch, foot, yard, mile B. volume cup, teaspoon, gallon, pint, quart C. weight ounce, pound (lb), ton D. temperature °F

Stating a Measurement In every measurement there is a ¨ Number followed by a ¨ Unit from measuring device

Number vs. Quantity Ø Quantity - number + unit UNITS MATTER!!

Learning Check What is the unit of measurement in each of the following examples? A. The patient’s temperature is 102°F. B. The sack holds 5 lbs of potatoes. C. It is 8 miles from your house to school. D. The bottle holds 2 L of orange soda.

Solution A. °F (degrees Fahrenheit) B. lbs (pounds) C. miles D. L (liters)

Metric System - standards of measurement used in science Units in the Metric System l length meter m l volume liter L l mass gram g l temperature Celsius °C

Learning Check Identify the measurement in metric units. A. John’s height is 1) 1. 5 yards 2) 6 feet 3) 2 meters B. The volume of saline in the IV bottle is 1) 1 liters 2) 1 quart 3) 2 pints C. The mass of a lemon is 1) 12 ounces 2) 145 grams 3) 0. 6 pounds

Solution A. John’s height is 3) 2 meters B. The volume of saline in the IV bottle is 1) 1 liter C. The mass of a lemon is 2) 145 grams

International System of Units § Metric system is now revised as the § § International System of Units (SI), as of 1960 Based on 10 or multiples of 10 Used in most of the world Used by scientists and hospitals 7 base units Table 1 -3, page 12

SI Base Units Quantity Symb Base Unit Abbre ol v. l Length meter m Mass m kilogram kg Time t second s Temp T kelvin K Amount n mole mol

Derived Units Ø Combination of base units. 1 cm 3 = 1 m. L w length 1 dm 3 = 1 L Ø Volume (m 3 or cm 3) Ø Density (kg/m 3 or g/cm 3) w mass per volume M D= V

Volume § The space occupied by any sample of matter § Calculated for a solid by multiplying the length x width x height § SI unit = cubic meter (m 3) § Everyday unit = Liter (L), which is non-SI

Volume l l l l 20 1 Liter is the volume of a cube 1 dm (10 cm) on a side 1 L = 10 cm x 10 cm 1 L = 1000 cm 3 1/1000 L = 1 cm 3 1 m. L is about 20 drops of water or 1 sugar cube 1 L about 1/4 of a gallon - a quart

Learning Check Match 1) length 2) mass 3) volume ____ A. A bag of tomatoes is 4. 6 kg. ____ B. A person is 2. 0 m tall. ____ C. A medication contains 0. 50 g Aspirin. ____ D. A bottle contains 1. 5 L of water.

Solution Match _2 A. 1) length 2) mass 3) volume A bag of tomatoes is 4. 6 kg. _1_ B. A person is 2. 0 m tall. _2_ C. A medication contains 0. 50 g Aspirin. _3_ D. A bottle contains 1. 5 L of water.

SI Prefix Conversions Prefix mega- Symbol M Factor 106 kilo- k 103 BASE UNIT --- 100 deci- d 10 -1 centi- c 10 -2 milli- m 10 -3 micro- 10 -6 nano- n 10 -9 pico- p 10 -12

Metric Prefixes n Increase or decrease basic unit by 10 n Indicate a numerical value prefix = value 1 kilometer = 1000 meters 1 kilogram = 1000 grams

Prefixes that Increase A Unit Prefix Symbol giga- G mega 000 kilo- Value 1 000 000 M k 1 000

Prefixes that Decrease A Unit Prefix Symbol decicentimillimicronano d c m (mu) n Value 0. 1 0. 001 0. 000 000 0001

Learning Check Select the unit you would use to measure A. Your height 1) millimeters kilometers B. Your mass 1) milligrams 2) meters 2) grams 3) 3) kilograms C. The distance between two cities 1) millimeters kilometers 2) meters 3) D. The width of an artery 1) millimeters kilometers

Solution A. Your height 2) meters B. Your mass 3) kilograms C. The distance between two cities 3) kilometers D. The width of an artery 1) millimeters

Learning Check Indicate the prefix to use for 1. A mass that is 1000 times greater than 1 gram 1) kilo 2) milli 3) mega 2. A length that is 1/100 of 1 meter? 1) deci 2) centi 3) milli 3. A unit of time that is 1/1000 of a second. 1) nanosecond 2) microsecond 3) millisecond

Solution 1. 1) kilo 2. 2) centi 3. 3) millisecond