Lab+1_+Metric+System+and+Conversions copy copy

Introduction to Human Physiology Lab BIO 240L L The Metric System Mathematics is a very important component of all the sciences. Many of the concepts you will be learning in Human Physiology are represented by numbers, particularly in the form of graphs and charts. Scientists use the Metric System; also called the Système Internationale (French for International System) abbreviated SI. The SI is very convenient because it allows the quick conversion of measurement into different units. This can easily be done because the SI system has a base 10. For example, there are 1000 milli-units in one unit, 100 centi-units in 1 unit, 10 deci-units in 1 unit and so forth. The English System used commonly in the United States, England, and other countries uses units that are NOT base 10 and have no mathematical base. Therefore it is harder to make conversions. For example, there are 12 inches in 1 foot, but 12 feet do not make a yard. The first concepts you should review are the units of measurement. A. Units of Measurement : Units that allow the accurate measurement of different quantities. a. Mass : Measured by the unit gram (g). This is a measurement of matter. Matter and weight are different concepts. Matter takes up space, while weight is the result of the gravitational pull of the earth on that object. How can you tell the difference? How much do you weigh? What size pants do you wear? On earth your weight and matter are the same, but if you travel to the moon (where the gravitational pull is less) you will weigh LESS, but the size of your pants will be the same. Your mass has not changed, but your weight has changed . b. Length : Measured by the unit meter, also called metre (m). This is a measurement of two dimensional space. You are measuring a straight line and lines can be broken into smaller and smaller pieces (to infinity). So the meter as well as other measurements can be divided into smaller and smaller units. c. Volume : Measured by the unit liter (l). This is a measurement of displacement; how much of a medium (i.e. water or air) is displaced by a mass. How much does the water in the tub raise after you get in? This measurement is related to the mass of the object NOT the weight. Note that for our purposes in this lab mass and weight will be used interchangeably. d. Pressure : Measured by the units atmospheres (atm) or millimeters of mercury (mmHg). The atmosphere is ~100 kilometers high. The weight of this air mixture exerts a force on an object at sea level equivalent to 1 atm. 1 atm is enough pressure to move mercury inside a column by 760 mm (760 mmHg = 1 atm). See your lecture book for a more in depth explanation. e. Temperature : Measured by the units degrees Celsius (˚C) or degrees Kelvin (K). This is a measurement of molecular movement. Molecules that are moving very fast have higher temperatures than molecules moving slowly. What molecules do you think are moving faster, molecules of ice water or molecules of boiling water? The range for degrees Celsius is based on the boiling point of pure water (100˚C) and the freezing point of water (0˚C) . B. Reminder about the Exponential Notation: Exponential notation is based on powers of the base number 10, and is very useful for expressing very large or very small numbers. The number 100,000,000,000 for example, takes up a lot of room and takes time to write out, while 10 11 is much more efficient. 1

Introduction to Human Physiology Lab The line below shows the equivalent values of decimal notation (the way we write numbers usually, like "1,000 dollars") and scientific notation (10 3 dollars). For numbers smaller than one, the fraction is given as well. Fraction 1/1000 1/100 1/10 Decimal notation 0.001 0.01 0.1 1 10 100 1,000 Exponential notation 10 -3 10 -2 10 -1 10 0 10 1 10 2 10 3 C. Now that you know the basic units of measurement of the SI system, you should learn the equivalent measurements. Remember that the SI system is based on units of 10 so that 100 can also be written as 10 X 10 or 10 2 (the superscript is called an exponent which indicates the number of times you multiply by 10). How about if we want to represent a small number? 0.1 = 10 divided (/) by 100 or 10/10 2 which is equal to 10 -2 . So, numbers LARGER than the unit have positive exponents while numbers SMALLER than the unit have negative exponents. D. The SI system uses prefixes (words that are placed before another word to change the meaning) to represent whether a value is larger or smaller than the unit. Study the following prefixes: Prefix Abbreviation Division of SI unit Exponent Name pico (p) 0.000000000001 10 -12 trillionth nano (n) 0.000000001 10 -9 billionth micro (μ) 0.000001 10 -6 millionth milli (m) 0.001 10 -3 thousandth centi (c) 0.01 10 -2 hundredth deci (d) 0.1 10 -1 tenth Unit 1 10 0 deka (da) 10 10 1 ten hecto (h) 100 10 2 hundred kilo (K) 1,000 10 3 thousand mega (M) 1,000,000 10 6 million giga (G) 1,000,000,000 10 9 billion Note: μ is a symbol for the prefix micro and is a Greek letter. E. Now that you know the prefixes, exponents, and divisions of a unit, you are ready for some calculations. There are several ways to get to the right answer, so you should find a method that works for you. As you have noticed above, the value of a number is determined by the place of the decimal point, so you can change the value of a number by moving the decimal point to the right (the number becomes bigger) or to the left (the number becomes smaller). This is an easy method that requires memorization of the rules or some simple reasoning. For example take the following conversions: i. 1 meter is equal to how many centimeters? 100 2

Introduction to Human Physiology Lab Some SI to English conversion factors: Some English to SI conversion factors: Mass: 1 Kilogram (Kg) = 2.205 pounds (lbs) 1 pound (lbs) = 0.4536 Kilogram (Kg) 1 gram (g) = 0.0022 pounds (lbs) 1 pound (lbs) = 453.6 grams (g) 1 gram (g) = 0.035 ounces (oz) 1 ounce (oz) = 28.35 grams (g) ************************************************************* Length: 1 millimeter (mm) = 0.039 inch (in) 1 inch (in) = 25.40 millimeter (mm) 1 meter (m) = 3.281 feet (ft) 1 foot (ft) = 0.305 meters (m) 1 meter (m) = 1.094 yards (yd) 1 yard (yd) = 0.914 meters (m) 1 Kilometer (Km) = 0.621 mile (m) 1 mile (m) = 1.609 Kilometer (Km) ************************************************************** Volume: 1 liter (l) = 1.76 pints (p) 1 pint (p) = 0.568 liters 1 liter (l) = 0.220 gallon (g) 1 gallon (g) = 4.546 liter 1 g of pure water occupies 1 cc of volume and displaces 1 ml of medium; 20 drops of water = 1 milliliter (ml) A cubic centimeter (cc) = 1 milliliter (ml) ************************************************************** Temperature : To convert from Celsius/Centigrade (C) to Fahrenheit (F) use the formula: Fahrenheit = 9/5(C) + 32 To convert form Fahrenheit to Celsius, use the formula: Celsius = 5/9 (F – 32) To convert from Kelvin (K) to Fahrenheit, use the formula: Fahrenheit = 9/5 (K - 273.15) + 32 To convert from Kelvin to Celsius, use the formula: Celsius = K - 273.15 4

Introduction to Human Physiology Lab BIO 240L Student Name: Jirolna Joseph_______________________ Lab 1: SCIENTIFIC MEASUREMENTS This exercise should be completed during lab. You may work with a lab partner. Refer to the conversion factor table on the previous page to perform your calculations. Please return to your desk to perform calculations after collecting data from the following stations. This will alleviate congestion as others are waiting to use the station. The asterisk (*) denotes measurements/calculations that should be performed at your desk. 1. LENGTH : (0.25 points each – 1 point) a. *Measure the diameter of a penny in mm: 18 mm b. *Convert to centimeters: 1.8 cm c. Measure the diameter of the period at the end of this sentence. Too small to measure Is it too small to measure accurately with the ruler provided? Yes_____ (it is 100 µm, the size of the largest human cell) d. *Measure the distance between these two points . . in mm: e. Measure the distance between these two points . in mm: too close Can't? They are too close and you can't distinguish them as two separate points. This is called resolution . Our eyes have a resolution of 10 micrometers which means that anything smaller has to be magnified (seen only through a microscope). f. Measure your height in inches: 65 inches g. *Convert to meters: 1.651 2. MASS : (0.25 points each – 1 point) a. Measure the weight of a penny in grams: 2.49 b. *Convert to milligrams (mg): 2490 5

Introduction to Human Physiology Lab Density of H 2 O = 0.82_____ g /ml *Use the instructions from parts 2 (how to calculate mass) and 3 (how to calculate volume) to perform to determine the density in the questions below: b. *What is the density of the wooden pencil? Include the appropriate units. Mass 2.80 g__________ Volume 2ml________ Density 2.80g/ml___________ (0.5 point) c. Does the pencil float in the water? Yes_______ Why? (1 point) ________________ The pencil floats because the mass of it is lighter than the volume. ________________________________________________________________ d. What is the density of the marble? Include the appropriate units. Mass 5.16__________ volume 3ml__________ Density 5.16g/ml__________ (0.5 point) e. Does the marble sink in the water? Yes______ Why? (1 point) ________________ The marble sinks because the mass of it is heavier than the volume. ________________________________________________________________ 5. Temperature : (0.25 points each; 2 points total) Measure the temperature of the following items by using a thermometer. Handle the thermometer with care. If it breaks, notify your instructor immediately. a. Temperature of the room in °Centigrade/Celsius: 20 _____ b. *Calculate temperature of the room in °Fahrenheit: 68 c. *Calculate temperature of the room in °Kelvin: 293.15___________________________ d. Temperature of boiling water in ° Centigrade: 90 e. *Calculate temperature of boiling water in ° Fahrenheit: 194 f. *Calculate temperature of boiling water in °Kelvin: 363.15 _____ g. Temperature of freezing water in ° Centigrade: 0 h. *Calculate temperature of freezing water in ° Fahrenheit: 32 7

Introduction to Human Physiology Lab i. *Calculate temperature of freezing water in ° Kelvin: 273.15______________________ Do the following measurement by placing the thermometer under your arm over your clothes. Wait for two minutes before reading it. Use an alcohol swab to clean it when finished. g. Your body temperature in °Centigrade: 20 h. *Calculate your body temperature in ° Fahrenheit: 68 i. *Calculate your body temperature in ° Kelvin: 293.15___________________________ Provide one potential source of error for each of your recordings: (1 point) Length:__not starting the measurement at zero______________________________________________________________ Mass:__not setting scale to zero_______________________________________________________________ Volume:_having more than one item in cylinder _______________________________________________________________ Density:______not measuring mass in the right unit such as grams __________________________________________________________ Temperature:______touching the thermometer with bare skin could affect the temperature _____________________________________________________ 8