## Helpful math tips for journalists: ‘Math Tools for Journalists’ chapters 9-12

*May 12, 2009 at 1:57 pm* *
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By Patrick McCabe

Written May 12, 2009

**Directional Measurements**

**Time, Rate and Distance**

When working with time, rate and distance problems the most important thing is to keep the units of measurement the same.

If the rate is in miles per hour then the distance needs to be miles and the time needs to be hours. If anything is not the same it should be converted.

FORMULAS:

Distance= rate x time

Rate= distance/time

Time= distance/rate

**Speed, velocity, acceleration, g-force and momentum**

Speed and velocity are different. Speed measures how fast something is going while velocity indicates its direction. Acceleration measures how quickly something speeds and g-force is an acceleration measure. The “g” represents the normal force of gravity. Momentum is the force needed to stop an b=object in motion.

FORMULAS AND EXAMPLES:

Acceleration=(ending velocity – starting velocity)/time

If a car accelerates from s=zero to 60 in 30 seconds what is the rate of acceleration?

(60 mph – 0 mph)/30 seconds = 2mph per second

Momentum= mass x velocity

What was the momentum of a race car weighing 132 kilograms when it crashed into a wall if it traveling 150 mph?

Convert mph to kilometers per hour (kph): 105 mph x 1.6= 168kph

132 kilograms x 168 kph= 22,176 kilogram kilometers per hour

**Area Measurements**

Journalists can use area measurements in all different types of stories. It is useful for a journalist to know how to calculate perimeter when writing articles about new developments or construction projects. Area is also important for real estate, technical, feature and sports reports. Square feet and square yards are useful when checking reports on size and circumference and radius are important for dealing with stories on circular area.

FORMULAS:

Perimeter = (2 x length) + (2 x width)

Area (squares and rectangles) = length x width

Area (triangles) = .5 base x height

Circumference = 2P x radius

Area (circles) = 2P x (radius)^2

**Volume Measurements**

In the business world terms like ton, barrel, box and cord take on a specific meaning. Goods are often sold in volumes. A goods measurement can vary based on the market, knowing how to measure volume is a key component to selling any good.

**Liquid Volume**

Liquid measurements apply to liquids in recipes, bodies of water and other fluids.

EXAMPLES:

2 tablespoons = 1 fluid once

4 quarts = 1 gallon

1 U.S. standard barrel = 31.5 gallons

For finding the volume of a rectangular solid use this formula: Volume = length x width x height

Other measurements:

Cord: 128 cubic feet

Ton:

Short ton= 2,000 lbs

Long ton= 2,240 lbs

Metric ton= 2,204.62 lbs

**The Metric System**

Most Americans struggle to use the metric system yet the rest of the world uses it for every type of measurement. The metric system is an important tool for international commerce. It is based on the multiples of 10.

**Definitions**

Meter: basic unit for length

Mass: derived from meter and the unit for weight

Newton: unit of force

**Basics**

Because the metric system is based on the decimal system you can change from one unit to another simply by multiplying or dividing by any multiple of ten. Each unit is ten times as large as the next unit.

Prefixes can create larger or smaller factors when added to a unit name. The prefixes for numerical values are:

micro (1 millionth) 0.000001

milli (1 thousandth) 0.001

centi (1 hundredth) 0.01

deci (1 tenth) 0.1

no prefix 10

deka 10

hecto 100

kilo 1,000

mega 1,000,000

giga 1,000,000,000

tera 1,000,000,000,000

For a more in-depth explanation of the metric system click here.

Entry filed under: Math Tools. Tags: Area, Distance, Journalism, Journalists, Math Tools for Journalists, Metric System, Rate, Speed, Time, Velocity, Volume.

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