Measurement You are making a measurement when you

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?

What is a Measurement? • Measurement: a comparison of an the dimension of object or substance to a known standard. – Dimension: a physical property of an object, any measureable property of an object – Standard: a known quantity that is universally accepted – Tool: an artificial object used to aid the senses in determining known standards for measurements

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

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

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

What Universal System Do We Use? • SI- Systeme Internationale – Metric System- a system of measurement based on multiples or divisions of of 10 – Why? • It is convenient • It is universally used amongst scientists, doctors, mathematicians, etc.

Metric System • The metric system is based on a base unit that corresponds to a certain kind of measurement • Length = meter • Volume = liter • Weight (Mass) = gram • Prefixes plus base units make up the metric system – Example: • Centi + meter = Centimeter • Kilo + liter = Kiloliter

The Metric System • The metric system is a measurement system based on our decimal (base 10) number system. • Other countries and all scientists and engineers use the metric system for measurement.

Common Dimensions and Their Given Units of Measure Dimension Base Unit Mass Kilogram Volume Liter Time Seconds Temperature Kelvin Length Meter

What is the Length? • • • We can see the markings between 1. 6 -1. 7 cm We can’t see the markings between the. 6 -. 7 We must guess between. 6 &. 7 We record 1. 67 cm as our measurement The last digit an 7 was our guess. . . stop there

Learning Check What is the length of the wooden stick? 1) 4. 5 cm 2) 4. 54 cm 3) 4. 547 cm

Meters • One centimeter is about the width of a large paper clip • or your fingernail.

Meters • A meter is about the width of a doorway

Gram • Grams are used to measure mass or the weight of an object.

Grams • A milligram weighs about as much as a grain of salt.

Liters • Liters measure liquids or capacity.

Liter • 1 milliliter is about the amount of one drop

Changing Metric Units • To change from one unit to another in the metric system you simply multiply or divide by a power of 10.

Metric System • So if you needed to measure length you would choose meter as your base unit – Length of a tree branch • 1. 5 meters – Length of a room • 5 meters – Length of a ball of twine stretched out • 25 meters

Metric System • But what if you need to measure a longer distance, like from your house to school? – Let’s say you live approximately 10 miles from school • 10 miles = 16093 meters – 16093 is a big number, but what if you could add a prefix onto the base unit to make it easier to manage: • 16093 meters = 16. 093 kilometers (or 16. 1 if rounded to 1 decimal place)

Metric Prefixes • Metric Units • The metric system has prefix modifiers that are multiples of 10. Prefix Symbol Factor Number Factor Word Kilo- k 1000 Thousand Hecto. Deca. Unit Deci. Centi. Milli- h da or dk m, l, or g d c m 100 10 1. 1. 001 Hundred Ten One Tenth Hundredth thousandth

To change from a larger unit to a smaller unit, you need to multiply. 1 km x 1000 = 1000 m 1 m x 100 = 100 cm 1 cm x 10 = 10 mm

To change from smaller units to larger units you divide by a power of ten. 1000 mm ÷ 10 = 100 cm ÷ 10 = 10 dm ÷ 10 = 1 m

Metric System • The three prefixes that we will use the most are: – kilo – centi – milli Base Units kilo hecto deca meter gram liter deci centi milli

Metric System • These prefixes are based on powers of 10. What does this mean? – From each prefix every “step” is either: • 10 times larger or • 10 times smaller – For example • Centimeters are 10 times larger than millimeters • 1 centimeter = 10 millimeters Base Units kilo hecto deca meter gram liter deci centi milli

Metric System – Centimeters are 10 times larger than millimeters so it takes more millimeters for the same length 1 centimeter = 10 millimeters Example not to scale 40 1 mm 40 1 cm 41 1 mm 1 mm 1 mm 41

Metric System • For each “step” to right, you are multiplying by 10 • For example, let’s go from a base unit to centi 1 liter = 10 deciliters = 100 centiliters ( 1 x 10 = 10) = (10 x 10 = 100) 2 grams = 20 decigrams = 200 centigrams (2 x 10 = 20) kilo hecto deca meter liter gram = (20 x 10 = 200) deci centi milli

Metric System • Now let’s try our previous example from meters to kilometers: 16093 meters = 1609. 3 decameters = 160. 93 hectometers = 16. 093 kilometers • So for every “step” from the base unit to kilo, we moved the decimal 1 place to the left (the same direction as in the diagram below) kilo hecto deca meter liter gram deci centi milli

Metric System • If you move to the left in the diagram, move the decimal to the left • If you move to the right in the diagram, move the decimal to the right kilo Hecto Deca meter liter gram deci centi milli

Metric System • Summary – Base units in the metric system are meter, liter, gram – Metric system is based on powers of 10 – For conversions within the metric system, each “step” is 1 decimal place to the right or left – Using the diagram below, converting to the right, moves the decimal to the right and vice versa kilo hecto deca meter liter gram deci centi milli

Place Values of Metric Prefixes cm cg c. L Thousandth dm dg d. L Hundredth m g L Tenth dkm dkg dk. L One hm hg h. L Ten Hundred Thousand km kg k. L mm mg m. L

Place Values of Metric Prefixes Move the decimal point to the right to multiply. cm c. L cg Thousandth dm d. L dg Hundredth m L g Tenth dkm dk. L dkg One hm h. L hg Ten Hundred Thousand km k. L kg mm m. L mg

Place Values of Metric Prefixes cm cg c. L Thousandth dm dg d. L Hundredth m g L Tenth dkm dkg dk. L One hm hg h. L Ten Hundred Thousand km kg k. L mm mg m. L

Place Values of Metric Prefixes Move the decimal point to the left to divide. cm c. L cg Thousandth dm d. L dg Hundredth m L g Tenth dkm dk. L dkg One hm h. L hg Ten Hundred Thousand km k. L kg mm m. L mg

Place Values of Metric Prefixes km kg k. L hm hg h. L dkm dkg dk. L m g L dm dg d. L cm cg c. L mm mg m. L 3 km 30 hm 300 dkm 30000 dm 300000 cm 3000000 mm 4 L 12 cm

• Accuracy and Precision