B. VOLUME. The metric base unit for volume is the liter (L), which is slightly more than a quart.

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1 Measurement Lab 3 OBJECTIVE To become familiar with basic measurements and units used in the sciences. In science, the metric system is utilized to make measurements. One advantage of the metric system is that it is based on units of ten, making conversions from unit to unit easier. This section of the lab will provide you with a brief overview of some measurements often used in science and the health professions. [Kilo (k) Hecto (H) Deka (D) Base Deci (d) Centi (c) Milli (m)]... Micro (μ)... Nano (n) A. Length The metric base unit for length meter. Learn the relationships of the following related units and make the conversions indicated. (See Metric System Table). Meter (m) Centimeter (cm) Millimeter (mm) Micrometer/micron (µm) Nanometer (nm) Angstrom (Å) Convert the following: 345 cm = mm 160 km = m 2500 µm = mm 11 cm = nm 1 mm = m 200 nm = mm 1 Å = nm B. VOLUME The metric base unit for volume is the liter (L), which is slightly more than a quart. Approximate Comparisons (1) 12 oz. Soda = 360 ml (1) fluid ounce = 30 ml (cc) (1) teaspoon = 5 ml (cc) (1) gallon = L Convert the following: 1 L = ml 5 oz. = ml 5 sodas = ml 1 L of medicine will make how many 5 ml injections? Injections C. MASS Mass is the amount of matter in an object and it is constant. The unit of mass is the gram. Doses of medicine are usually milligrams or micrograms, while body weight is measured in kilograms. Convert the following: A 70 kg man = lbs. 300 g = mg 4000 µg = mg Mr. Mister weighs 195 lbs. He receives a dose of medicine at 2 mg/kg body weight. How much medicine does he receive? 520 g = mg 4250 µg = g QUESTIONS SIMILAR TO THESE WILL APPEAR ON YOUR EXAMS NOTE When converting to a smaller unit, the number increases so move the decimal point will to the right. When converting to a larger unit, the number will decrease so move the decimal point to the left. 17 ch03.indd 17

2 18 Lab 3 Measurement PART D QUESTIONS 1. How many inches equal 1 millimeter? 2. The prefix kilo means 3. What instrument would you use to measure about 1 / 3 cup of fluids in the metric system? 4. What units would the above measurement be in if it were a large amount of fluid (to fill a bathtub)? 5. What units would the measurement be in if you were measuring a small amount of fluids (a full eyedropper)? PART E USING MEASUREMENTS You can use metric measurements to estimate the size of an object under the microscope. You must begin by measuring the field of vision on the microscope with a metric ruler. EXAMPLE A metric ruler was placed in the field of vision with the 10x objective in place. The ruler under the field of vision is shown below: Courtesy of Michael Cryder 1. Assume the marks on the diagram above designate mm. What would the size of the field of vision be on the diagram above? 2. Place a metric ruler under each objective lens on your own microscope and measure the fields of view. The space between each visible line is equal to one millimeter. Record the measurement below: 4 = mm 10 = mm 40 = mm ch03.indd 18

3 Lab 3 Measurement 19 EXAMPLE (continued) 3. Now that you have the size of your fields of vision, remove the ruler. You should NOT have to measure again as long as you use the same microscope. You can now use this information to estimate the size of an object in the field of vision. TRY THIS PRACTICE PROBLEM FIRST 3 mm Courtesy of Michael Cryder a. To find the length of one cell in the field of vision above, you would first visualize and estimate how many cells would fit across the length of the field of vision. In this case, approximately 6 cells fit across the length of the field. The length of one cell can be calculated using the following formula: Diameter of field # Cells visible = Size of cell b. If you plug in the proper numbers, you will find the answer by calculating: 3 mm 6 cells The answer is: mm c. Now calculate the height of one cell using the same method (show your work): The answer is: mm (continued) ch03.indd 19

4 20 Lab 3 Measurement EXAMPLE (continued) 4. Find the slide of three-colored strings in your slide box and focus it in on low-power (10 ) on your microscope. a. Use the method that you have just learned to estimate the width of one string (pick one of the colored strings and estimate how many times it will fit across the field of vision). b. Do the calculations and show your work below: The width of the color string is mm PART F QUESTIONS 1. How many millimeters equal an inch? 2. Ten cells are visible across the width of the microscope field using the 4x objective lens and four cells are visible along its length. Calculate the dimensions of the cell in both millimeters and micrometers. (mm) (µ) LENGTH OF THE CELL WIDTH OF CELL ch03.indd 20

5 Lab 3 Measurement 21 THE METRIC SYSTEM TABLE MEASUREMENT UNIT AND ABBREVIATION METRIC EQUIVALENT METRIC TO ENGLISH ENGLISH TO METRIC 1 kilometer (km) = 1000 (10 3 ) m 1 km = 0.62 mile 1 mile = 1.61 km 1 meter (m) = 100 (10 2 ) cm = 1000 mm 1 m = 1.09 yards (yd) 1 m = inches (in) 1 yard = m 1 foot = m LENGTH 1 centimeter (cm) = 0.01 (10 2 ) m 1 cm = in 1 foot = 30.5 cm 1 inch = 2.54 cm 1 millimeter (mm) = (10 3 ) m 1 mm = in 1 micrometer (µm) = (10 6 ) m 1 nanometer (nm) = (10 9 ) m 1 angstrom (Å) = (10 10 ) m AREA 1 square meter (m 2 ) = 10,000 cm 2 1 m 2 = sq. yards 1 m 2 = sq. feet 1 sq. yard = m 2 1 sq. foot = m 2 1 square centimeter (cm 2 ) = 100 mm 2 1 cm 2 = sq. inch 1 sq. inch = cm 2 1 metric ton (t) = 1000 kg 1 t = ton 1 ton = t MASS 1 kilogram (kg) = 1000 g 1 kg. = pounds (lb) 1 gram (g) = 1000 mg 1 g = ounce (oz) 1 g = grains 1 pound = kg 1 ounce = g 1 milligram (mg) = g 1 mg = grain 1 microgram (µg) = g (continued ) ch03.indd 21

6 22 Lab 3 Measurement (continued) MEASUREMENT UNIT AND ABBREVIATION METRIC EQUIVALENT METRIC TO ENGLISH ENGLISH TO METRIC VOLUME (SOLIDS) 1 cubic meter (m 3 ) = 1,000,000 cm 3 1 m 3 = cubic yds. 1 m 3 = cubic ft. 1 cubic centimeter (cm 3 or cc) = m 3 = 1 ml 1 cubic yd.= m 3 1 cm 3 = cubic in. 1 cubic in. = cm 3 1 cubic millimeter (mm 3 ) = m 3 1 kiloliter (kl) = 1000 L 1 kl = gallons (gal) 1 gal. = L VOLUME (LIQUIDS and GASES) 1 liter (L) = 1000 ml 1 L = gal 1 L = quarts (qt) 1 milliliter (ml) = L = 1 cm 3 1 ml = fluid oz. 1 ml = ¼ teaspoon (tsp) 1 ml = drops (gtt.) 1 qt. = L 1 qt. = 946 ml 1 pint = 473 ml 1 fluid oz. = ml 1 tsp. = 5 ml 1 microliter (µl) = L TIME 1 second (s) = 1 minute (min) 60 1 millisecond (ms) = s TEMPERATURE Degrees Celsius ( C) F = 9 C C = 5 ( F 32) 9 ch03.indd 22