Posted by: lcowie | December 8, 2008

Math Tools Ch. 3

Abridged Math Tools Chapter Three

by Lesley Cowie

tipsThis portion of Math Tools will discuss directional measurements, area measurements, volume measurements and the metric system. Journalists encounter stories with these components often. Rather than simply taking a bystander’s word for these measurements, journalists should figure out the measurements on their own.

The equation is the same for determining time, rate and distance. However, journalists should be sure to arrange the equation as needed. Therefore, distance equals rate multiplied by time. To find the rate, one would divide time into distance. Lastly, to find time, one would divide the rate into the distance.

Journalists should pay close attention to units of measurement. A mile and a nautical mile are different. A mile comprises 5,280 feet, whereas a nautical mile comprises 6,080 feet.

A knot is a measure of speed. One knot is one nautical mile per hour. If the time is given in minutes, a journalist should divide by 60 to convert it to hours before working the equation to find the distance.

One common mistake that journalists make is to think that speed and velocity are the same measurement. While they are used interchangeably, speed measures how fast something is going, and velocity indicates its direction. To calculate the average speed, or rate, one would divide time into distance.

Momentum is the force necessary to stop an object from moving. It is the product of mass and velocity.

Utilizing communications tools to explain measurements

Kathleen Wickham, author of “Math Tools for Journalists,” writes that there are two ways to explain measurements: by analogy and by using simple, accurate numbers.

Analogies allow readers to visualize a comparison and fully grasp the writer’s idea. It is more effective to say that the tree is as tall as a four-story building than it is to say that the tree is 40 feet tall.

This strategy fails when the reader does not understand the comparison. If a writer uses a localized comparison, it is unlikely that the national audience will understand the slang in the comparison.

Analogies also fail when numbers are essential. In some stories, the public wants to know the exact measurements of an item or property. In this case, an analogy would not further the audience’s understanding or perspective of the issue.

Simple, accurate numbers may be obtained through simple equations. Many people are familiar with the equation for area. Area deals with the size of surfaces and may be determined by multiplying length times width.

Perimeter becomes important in stories that discuss construction projects on the ground. This number will help readers understand how large the project is. One can find the perimeter by adding twice the length to twice the width.

Circumference and radius come into play when the project is circular. The radius is the measurement from the outside of the circle to the center point within the circle. This number, multiplied by the product of two and pi, will result in the circumference.

Calculating quantity and capacity

liquidVolume is an important measurement in the business world, from buying to selling. Goods are often sold based on volume. Volume is an important factor in determining the selling price of a good.

Journalists have to calculate volume when it comes to determining liquid measurements and rectangular solids. There are a variety of conversions that must occur when determining liquid measurements. Liquids come in many sizes, from tablespoons and ounces to quarts and gallons.

Determining rectangular solids is an easier process. This type of volume requires length, width and height measurements. After multiplying these three numbers together, one will see the resulting volume of the solid.

Firewood is sold by a measurement called a cord. A cord is made up for 128 cubic feet when the wood is neatly stacked in a line or row. Wickham describes a standard cord as a stack of wood 8 feet long, 4 feet wide and 4 feet high.

Beating the system

Although the metric system is not the primary system for measurement in the U.S., it is important for journalists to know. Because many other countries in the world use it, the metric system is important for international commerce and science.

The meter is the basic unit for length. Mass is derived from the meter. One gram is the mass of one cubic centimeter of water at 0 degrees Celsius. With this wording underway, it is easy to see why Americans enjoy using the metric system – or not.

Basically, the metric system is based on the decimal system. Users can change from one unit to another by multiplying or dividing by 10, 100, 1,000 or other multiples of 10. It is important to note that each unit is 10 times as large as the next smaller unit.

The primary units of measurement are as follows: meter (length), gram (mass) and liter (volume). When added to a unit name, prefixes create larger or smaller factors.

prefixThere are a series of conversions that a journalist can do to convert American measurements to metric and vice versa. Because there are so many numbers and terms to remember, many people consult a chart to do their conversions.

Fahrenheit is the standard unit for temperature in the U.S. However, many students become familiar with converting Fahrenheit to Celsius and vice versa through schooling.

To convert Fahrenheit to Celsius, one would subtract 32 from the Fahrenheit reading and then multiply this number by 0.56. To convert Celsius to Fahrenheit, take the product of the Celsius reading and 1.8 and add 32.

For the most part, units of measurement do not need to be capitalized. In special circumstances, such as with temperature (C for Celsius) or units derived from the name of a person or country (N for Newton), the units of measurement may be capitalized.

The National Institute of Standards and Technology suggests a few style rules for using these measurements. For instance, this organization believes that there should be a space between the number and the symbol to which it refers. This division of the U.S. Department of Commerce also says that a zero should be written before the decimal point in situations where the number is less than one.

Directional measurements, area measurements, volume measurements and the metric system are common numbers in society and journalism. These topics have fairly easy equations and conversions for journalists to use. It is important for journalists to note the particular units of measurement for each area of determination.


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