Measurement: Converting Distances

Transcription

1 Measurement: Converting Distances Measuring Distances Measuring distances is done by measuring length. You may use a different system to measure length differently than other places in the world. This is because there is more than one system you can use. The United States uses something called the English system. Other countries use something called the Metric system instead. The U.S. uses the Metric system sometimes. Yet in the U.S., English is the system that is used most often. Runners and cyclists travel yards, miles, or meters. These are all distances. Yards and miles are English system measurements. A meter is the standard unit (for length) of the Metric system. Each system is unique. The reason the United States has not converted over to the Metric system is simple. So many people know the English system and it is still taught in schools. Scientists hope one day there will be one universal system that is used across the world. The English System You should already recognize units in the English system. If you have ever measured anything with a ruler or traveled in a car then you have used the English system. The English system measures length by inches, feet, yards, and miles. -Inches - 1 foot = 12 inches 1 yard = 36 inches 1 mile = 63,360 inches -Foot- 12 inches = 1 foot 1 yard = 3 feet 1 mile = 5,280 feet 1

2 -Yard- 36 inches = 1 yard 3 feet = 1 yard 1 mile = 1,760 yards -Mile- 63,360 inches = 1 mile 5,280 feet = 1 mile 1,760 yards = 1 mile Converting using the English system It is easy to convert between inches, miles, feet, and yards if you know basic math skills. It is important to know how the values compare so you can convert one distance value to another. For example: 48 inches equals feet. We know that 12 inches = 1 foot. We must make the value of a letter until we know what that letter stands for. In this problem we will call x. 48 in. = x feet To get the value of x we divide each side by the values we know. 48 in = x ft. 12 in. = 1 ft 2

3 Then we cross multiply. 48 x 1 = x x = 12x 12x = 48 We need to isolate x to one side so we divide both sides by the number in front of x. 12x = x = 4 Our answer is = 48 in. is equal to 4 ft. This method works when converting smaller distances into larger distances: Note: You would use this when converting inches to feet, inches to yards, inches to miles, feet to yards, feet to miles, and yards to miles. If you want to convert a larger distance into a smaller distance this is what you need to do. 7 yards = feet (once again lets use x to represent ) We know that 1 yard = 3 feet. Let s cross multiply. 7 yd. = x ft. 1 yd. = 3 ft. 7 x 3 = 21 1 x x = 1 x 3 21 = 1x

4 21 = x The answer is 7 yards = 21 feet. Try these English system conversions on your own to see if you get the right answers, 1. 3 miles = x feet yards = x inches ,800 inches = x miles You can check your answers at the end of this lesson. The Metric System The Metric system is usually viewed as easier than the English system. In countries like Canada, the Metric system is the standard system of measurement. Cars do not travel by miles. Instead, they travel by kilometers. The standard measurement is a meter. To determine what is being measured the suffix is placed in front of the word meter. Here is a box listing Metric values that are the most commonly used. Metric Value Numerical Value Kilo meter (kilometer) 1000 Hecto-meter (hectometer) 100 Deka-meter (decameter) 10 Meter 1 Deci-meter (decimeter) 0.1 Centi-meter (centimeter) 0.01 Milli-meter (millimeter) The way to convert values is easier using the Metric system Kilometers = x meters 4

5 To figure this out we move a decimal place to the right if we are going from the top of the Metric scale to the bottom (i.e. kilometers to a lesser value such as meters or centimeters). Since meters are three levels below kilometers in our chart, we move the decimal point over 3 spaces to the right. One space to the right is 30,000. Two places to the right is 300,000. Three spaces to the right is 3,000,000. 3,000.kilometers is equal to 3,000,000 meters. The Metric system seems simple, but what if you want to convert a lesser distance into a larger distance? 2 centimeters = x hectometers To figure this out we move a decimal place to the left if we are going from the bottom of the Metric scale to the top (i.e. centimeters to a larger value such as dekameters or kilometers). Since hectometers are four levels above centimeters in our chart, we move the decimal point over 4 spaces to the left. One space to the left is 0.2 Two places to the left is 0.02 Three spaces to the left is Four spaces to the left is centimeters is equal to hectometers. Try doing the following problems on your own and see if you can get the right answers millimeters = x kilometers dekameters = x decimeters 5

6 Answers to sample problems The answers to our first set of sample problems (the English system) are: 1. 15,840 ft in miles How did you do? Here are the answers for the second set of sample problems (the Metric system): km 2. 50,000 dm Abbreviations Both the Metric and English systems use abbreviations to make labeling units easier. Here is a chart showing the basic abbreviations for both Metric and English system values. Metric Abbreviation English Abbreviation Kilometer km Miles mi Hectometer hm Yards yd Dekameter dam Feet ft Meter m Inches in Decimeter dm Centimeter cm Millimeter mm 6

7 Measurement: Converting Distances Worksheet Directions: Convert each value using the English System to find the value of x mi. = x ft in. = x ft yd. = x in. x = x = x = 4. 88,000 yd. = x mi mi. = x in in. = x yd. x = x = x = ,320 in. = x mi ft.. = x in in. = x ft. x = x = x = Directions: Convert each value using the Metric System to find the value of f hm = f mm ,019 cm = f dam km = f m f = f = f = 13. 8,000 mm = f km ,500 hm = f dm m = f dm f = f = f = mm = f cm dm = f dam m = f hm f = f = f = 7

8 Answer Key ,320 ft ft in mi ,800 in yd mi in ft ,000,000 mm dam ,000 m km ,500,000 dm dm cm dam hm 8