WORKSHEET 14 Using the International System of Units (SI)

1 SCIENCE SKILLS WORKSHEETS35 EXPERIMENTINGSKILLS Name _____ Date_____ Class _____Copyright by Holt, Rinehart and Winston. All rights SKILLS14 Using the International System of Units (SI)In the United States, few people besides scientists use the InternationalSystem of Units (known as SI for Syst me Internationale d unit s) regu-larly. SI is becoming more common for two reasons. Once you learn and practice SI, it is easier to use than the standardEnglish System . As communication systems and businesses become increasinglyglobal, there is a growing need for a worldwide standard measure-ment are reasons why students are required to learn SI in school. Wealready use SI for many things. For instance, most beverages are soldin 2 L or 3 L bottles. What other items are measured with SI Units ?Match Em Up!

2 Match the SI unit with the dimension that it square the SI prefix with its you read, watch for words such as nanosecond, kilocalorie, milliliter,and SI ConversionChart is provided foryou in Appendix I onpage is on the way!36 HOLT SCIENCE AND TECHNOLOGYName _____ Date_____ Class _____Using the International System (SI), continuedConversionsConvert between SI and English Units with the following factors :massvolumedistance1 lb 454 g1 gal L1 ft m1 g lb1 L gal1 m ftThere is a handy method of doing conversions based on this figure:Here s an example: How many centimeters is 38 ft?Step 1: Put the known quantity in the upper-left space, as follows:Step 2:Put a conversion factor (also called an equality) in thenext set of boxes to the right. Make sure that the Units matchdiagonally.

3 We started with feet on top, so we ll put feet on thebottom when we fill in the conversion factor, as follows:Note: There are two conversion factors listed above for feet andmeters. You can use either one as long as you put feet on the 3:Cross out, or cancel, the Units that appear on both thetop and the bottom, as follows:Step 4:Now ask, Is the unit that s not crossed outthe one Iwant? If the answer is yes, then continue to Step 5. If the answer is no, return to Step our example, the unit that s left is meters. We re looking for cen-timeters, so we ll return to Step 2: Remember to match Units by Holt, Rinehart and Winston. All rights ft38 m1 ft38 m1 ft38 m1 ft100 cm1 mSCIENCE SKILLS WORKSHEETS37 EXPERIMENTINGSKILLS Copyright by Holt, Rinehart and Winston. All rights the International System (SI), continuedStep 3: Cross out the matching 4: Is the unit that s not crossed outthe one I want?

4 Yes,we ve got centimeters, so we re ready to solve the 5:To solve the problem, multiply the numbers on the top row:38 100 1,159 Then multiply all of the numbers on the bottom row:1 1 1 Now, divide the top row s product by the bottom row s product:1,159 1 1,159 The answer is 1,159 cm!Your TurnThe following problems will help you practice your metric-to-metric,English-to-SI, and SI-to-English conversions. Be sure to show many meters is 1,602 ft? many pounds is 12 g? many gallons is L? many deciliters is 5 L? (Hint: How many deciliters are in 1 L?) many meters is cm?38 m1 ft100 cm1 mName _____ Date_____ Class _____38 HOLT SCIENCE AND TECHNOLOGYC opyright by Holt, Rinehart and Winston. All rights _____ Date_____ Class _____WORKSHEETEXPERIMENTING SKILLSM easuringTry this puzzle.

5 Suppose that you are given a bottle of water and threebeakers. One of the beakers holds 30 mL, one holds 40 mL, and thelargest of the three beakers holds 200 mL when full. There aren t anymarkings on any of the beakers. Describe how you could put exactly20 mL of water in the large beaker without Using any other of the TradeYou probably already know that beakers are used for measuring liquidvolume. We say that the dimension of measurementfor a beaker isvolume. Examine the following chart, and fill in the empty measurements and accurate readings are very importantaspects of scientific experimentation. Here are some pointers for accurately measuring the volume of a liquid: Place the container on a flat surface. Make sure the container is at eye level when you read the volume. If you have trouble seeing the level, hold a blank piece of paperbehind the container while you read the volume of the deviceDimension of measurementbeakervolumestopwatchbeam balancegraduated cylinderdistance or lengthtemperatureSCIENCE SKILLS WORKSHEETS39 EXPERIMENTINGSKILLS Copyright by Holt, Rinehart and Winston.

6 All rights _____ Date_____ Class _____Measuring, continuedIn a graduated cylinder or beaker, mostliquids form a meniscus,or a curved uppersurface. A meniscus is caused by surface ten-sion. When a liquid, such as water, is moreattracted to the walls of the container thanto itself, it curves up at the edges like asmile. When some liquids, such as mercury,are more attracted to themselves than to thewalls of the container, they curve down likea you read the volume of a liquid,read it from the center of its meniscus,not from the curved practice, read the volume of the following liquids. Each longergraduation represents one Volume: _____2. Volume: _____Uncertainty in MeasurementAnne brought a 1 L bottle of vinegar from home to use in an experi-ment on volcanoes in science class. She poured the contents of thebottle into a large beaker and carefully measured it.

7 She was surprisedto find that the vinegar s measured volume was actually L. Annethought the bottle contained exactly 1 L of vinegar. What possibleexplanations can you think of for the difference?Accuracy in MeasurementNo measurement is 100 percent accurate. All measurements have somedegree of uncertainty. When taking measurements, you should alwaysask yourself, How accurate is this measurement? For a measurement to be of any worth, it must have something thatindicates its reliability. A measurement s accuracy is expressed as itspotential amount of error. For instance, the smallest unit of measure-ment on a metric ruler is usually a millimeter. The most accurate mea-surement you could possibly make with that ruler is to the nearestmillimeter; thus, the measurement s accuracy is + mm. This is important because not all measurements have the same accu-racy.

8 The total accuracy of your work is only as reliable as your leastaccurate measurement. Following is an example:Ricardo added the following three liquids to a beaker: mL of liquid A mL of liquid B 250 mL of liquid C40 HOLT SCIENCE AND TECHNOLOGYName _____ Date_____ Class _____Measuring, continuedCopyright by Holt, Rinehart and Winston. All rights SKILLS WORKSHEETS41 EXPERIMENTINGSKILLS Copyright by Holt, Rinehart and Winston. All rights _____ Date_____ Class _____Measuring, continuedRicardo measured liquids Aand Bwith a narrow graduated cylinderthat had markings for every mL. He measured liquid Cin a beakerthat had markings only for every 10 mL. Thus, the volume of liquid Cwas only accurate to within about 5 mL. As a result, Ricardo correctly stated that the total volume of the mix-ture in the beaker was ( 250) mL 260 mL 5 the measurement devices below with their level of metric ruler with markings as smallas graduated cylinder with markings assmall as 2 scale with markings as small as thermometer with markings as smallas 1 1 1 CThink of accuracy in terms of someone says, That costsabout $20, which of the followingwould you think is most accurate:(a) the price is correct, give or take$10; (b) the price is correct, give ortake $1; or (c) the price is correct,give or take 1 cent?

9 The most accu-rate estimate is probably (b).The next time your family buysgasoline, pay attention to howaccurately the gas pump tracksthe volume of gas very accu-rately! For contrast, notice howaccurately the car s gas gaugemeasures the amount of gas inthe gas tank not very accurately!TRYTHIS!TROUBLESHOOTING