Real World Metric System

Transcription

1 Real World Metric System Each table has been given a Nutrition Facts sheet from a well-known fast food restaurant. Notice that serving sizes and quantities of fats, sugars, etc. are listed using grams (g) or milligrams (mg). These are units of measure in the International System of Units, commonly called the metric system. The metric system is the only system of measurement used in most countries worldwide and in science. In the United States, we tend to use the English system of measurement, for example ounces or pounds. Since all measurements throughout your scientific career should be stated in metric system units, this lab will serve to introduce you to the metric system, and how to convert English system units to those of the metric system. The metric system is easy and convenient to use. Table 1 lists some common metric units of measurement and their English system equivalents. Notice that within each category the units vary by powers of 10, which makes conversion from one unit to another very easy within the metric system. Table 2 lists the relative value of commonly used prefixes in the metric system. Table 2 also lists those relative values in scientific notation. Scientific notation is commonly used in science as a type of short-hand when dealing with very small or very large numbers. Notice that the exponent number is the number of decimal places either after (for large numbers a positive exponent) or before (for small numbers a negative exponent) the base unit. Table 1. Some important details about the metric system. The following information is to help you complete this lab and prepare for the lab practical. Therefore, you need to spend some time learning the parts your lab instructor wants you to know for the lab practical.

2 Table 2. Meaning and Value of Metric Prefixes The following information is to help you complete this lab and prepare for the lab practical. Therefore, you need to spend some time learning the parts your lab instructor wants you to know for the lab practical In this lab, you will Become more familiar with and learn to use the metric system Use a scale, ruler, and graduated cylinders to measure volume and length Convert English system measurements to metric and vice versa Learn to make conversion within the metric system (ex. grams to milligrams) Become more familiar with and learn to use scientific notation You Are What You Eat Using the Nutrition Fact sheets provided, each table (group of 4) will order a hypothetical meal sandwich, side, drink, and dessert. Your meal: Mass. Also referred to as weight, describes how heavy and item is. Using the Nutrition Fact sheet, determine the total amount (in both metric units and English equivalents) of the following in the entire meal: Total Fat: Salt (sodium): Sugar (under carbohydrates):

3 Using the balance provided measure out 1 gram of fat, salt, or sugar using the Crisco, table salt, or granulated sugar provided by the instructor. Next, use the scale to measure out the total fat, salt, or sugar in your meal. What is your impression of the quantity you measured? Draw an equivalent size on the back of this sheet so you will have something to refer back to. Were you surprised or did you already have some concept of these masses? Length. The distance between two points. What is the length of a 6 inch Subway sub in millimeters(mm), centimeters(cm), and meters(m)? Using the ruler provided, measure the diameter of a penny. Report the length in inches, cms, and mms. What is your height in English Units & in Metric Units? Use the conversion Table 1 to convert from English to Metric and then use the metric yard stick at your table to check your answer. How accurate were you? Volume. The space occupied by an object. How many milliliters(ml) are in a 16 ounce(oz) bottle of soda? How many liters(l)? Choose an appropriate graduated cylinder from the instructors bench to measure out the volume above (in mls) using tap water. How many ls are in a gallon of water? (there are 4 quarts in a gallon)

4 Area. A hectare is 10,000 square meters. You need to fence in a square piece of property with an area of one hectare. What length of fence do you need on each side of the square to complete the fence? Scientific Notation Restate the following numbers using proper scientific notation. For example 10,000 = 1x = 1x10-3 2,500 = 2.5x ,000 = 1,300,000 = 500 = 5,500,000,000 = = = = = Temperature. The degree Celsius ( C) is the basic unit of temperature in science and in most nations worldwide. Most people in the United States use the degree Fahrenheit ( F). Figure 1 shows a comparison of the two systems. Note some of the more common temperatures, such as the freezing and boiling points of water, common room temperature, and normal human body temperature.

5 Figure 1. Comparison of temperature scales. (From Univ. of Washington, Dept of Atmospheric Sciences)