3 HEED THESE RULES: It should be noted that: 1. You should always use DECIMALS (not fractions!) to express metric measurements. For example: write 2.25 cm, not 2 14 cm 2. If a metric measurement is less than one, precede the decimal with a ZERO. For example, don't write .55 mm, write 0.55 mm Points will be deducted for incorrect format. 1. LENGTH The basic unit of length in the metric system is the meter (m). Common derived units used in the laboratory are the centimeter (cm) (102 or 1/100 of a meter) and the millimeter (mm) (103 or 1/1000 of a meter). For measuring large distances, the kilometer (103 or 1000 meters) is often used. Obtain a wooden meter stick (1 meter in length) and a plastic metric ruler. Spend a few minutes looking at the meter stick and the ruler. Try to memorize how big the meter stick is, and how big the centimeters and millimeters on the ruler are. With your partner, estimate the sizes of the objects below, just to get a feel for thinking in metrics. Using the ruler or meter stick (whichever is more appropriate) go and measure the objects. Was your estimate close? Record below: Object: Width of door (meters) Estimate: m Measurement: m Length of chalkboard (meters, entire board) m m Length of a dollar bill (centimeters) cm cm Width of your pen (millimeters) mm mm Thickness of a dime (millimeters) mm mm Which of your fingernails is closest to 1 cm in width? 2 Figure 2.2 Common metric system prefixes and their values Prefix Symbol Value Superunit Kilo K Thousand 1000.0 Hecto h Hundred 100.0 103 102 Deca da Ten 10.0 10 300 . Unit Meter m One 1.0 1 Gram g Liter 1 Subunit Deci d Tenth 0.1 10-1 Centi C Hundredth 0.01 10-2 Milli m Thousandth 0.001 10-3 Micro P Millionth 0.000001 10-6 Nano n Billionth 0.000000001 10-9 B. METRIC CONVERSIONS Conversions within the metric system can be made easily using a metric staircase. Each step of the staircase represents a ten-fold change in the value of the measure or a shift of the decimal point one place. Therefore, each step you move down the staircase represents multiplication by ten or a movement of the decimal one place to the right. Each step Mega Move decimal point to the left. C. MEASURING Figure 2.3 The Metric Staircase Meter, liter or gram Kilo Hecto Deca UNIT Deci Centi Milli On your laboratory table, you will find several measuring instruments such as a meter stick, graduated cylinder, balance and thermometer. Familiarize yourself with these tools. Your instructor will demonstrate how each is properly used. Micro Move decimal point to the right. up the staircase represents a division by ten or the movement of the decimal point one place to the left. Two steps up or down the staircase represents a movement of the decimal point two places to the left or right and three steps up or down the staircase represents a movement of the decimal point three places to the left or right. Your instructor will demonstrate how to make conversions within the metric system using the staircase. LAB 1A: THE METRIC SYSTEM AND MEASUREMENT OBJECTIVES: At the end of this lab, you should be able to: 1. Identify the standard units of the metric system and make conversions among units. 2. Measure using metric system units. INTRODUCTION: The purpose of this exercise is to practice using the metric system. To conduct a scientific investigation, a researcher must be able to make accurate measurements. In today's exercise you will become familiar with metric system units and converting between large and small metric units. In each of the sections that follow, you will first familiarize yourself with the appropriate metric unit until you have a "feel" for its size, then you will estimate the measurements of some everyday objects. Finally, you will measure the objects to see how close your estimates were. A. METRIC UNITS The International System of Measurement (SI), commonly called the metric system, is used by scientists worldwide and has been adopted as the official system of measurement by most countries. Unlike our traditional system of measurement (inch, foot, yard, mile), the metric system is based on standard units that can be easily converted by simply multiplying or dividing by ten. The standard metric unit for length is the meter. Gram is the standard unit of mass and liter the standard unit of volume. Scientists measure temperature in degrees Celsius (or Kelvin). Figure 2.1 Standard units of the metric system Measure Unit Example Length Meter (m) Height of a typical door handle (1 m = approx. 39 inches) Mass Gram (g) Mass of one dollar bill Volume Liter (1) (1 g = 0.035 oz) Volume of large fast food soda (1 1= approximately 1 quart) Temperature Celsius (C) Water freezes at 0C and boils at 100C Measurements are further expressed using a superunit prefix or subunit prefix. Superunits contain Greek prefixes to show multiples of the base unit, so they make the base unit larger. Latin prefixes, on the other hand, represent subunits that make the base unit smaller.