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This week's LabZone activity
Feb. 7, 2007
Keeping Up
Do you ever feel like you need to walk faster than your parents just to keep up with them? This is because of the difference in leg length between you and your parents. How much faster do you need to walk than your parents do? Can you use a walking test to determine how tall a person is?
Objective
In this experiment you will test if the height of a person is related to their walking pace, and if this information can be used to estimate the height of a person.
Introduction
A pedometer is an instrument that is often used by joggers or walkers to tell them how far a distance they have gone. The name pedometer comes from the Latin words "ped," which means to walk, and "meter," which means to measure. On some pedometers when a person sets the instrument before an outing, they must enter their height into the pedometer to get an accurate reading. Why is height an important variable for measuring how far a person has walked?
One part of the answer has to do with ratios, which are fractions that are used to describe the relationship between two measurements. Our bodies have many interesting ratios in them. For example, when your arms are outstretched the distance from the tip of one hand to the other is usually equal to your height. This type of ratio is called a one-to-one (written 1:1) ratio. There are other types of ratios as well, each describing how one part of the body relates to another in size. Because the length of a person's legs is related to a person's height by a ratio, the height of a person will effect how long of a step they take. The longer each step is that you take, the more distance you will travel when walking, jogging or running. This ratio, combined with the motions involved in walking, is how pedometers measure distances.
 | An example of a pedometer. | iStockphoto.com |
The measurements of a pedometer are based on the hypothesis that all people have common ratios and proportions, even if they are different heights. In this experiment, you can test this hypothesis by measuring the height of different individuals to see if this is related to the number of steps they take to walk a certain distance. Will the result be a ratio? Will the ratio of different volunteers be the same? Can you use the ratio to predict the height of a person by counting the number of steps they take to walk a certain distance?
Experimental Procedure and Additional Information
Used with permission. Copyright © 2002-2007 Kenneth Lafferty Hess Family Charitable Foundation. All rights reserved.
Sohn, Emily. 2006. Ants on stilts. Science News for Kids (Aug. 9). Available at http://www.sciencenewsforkids.org/articles/20060809/Note3.asp .
For more science project ideas, go to http://www.sciencebuddies.org/mentoring/areas_of_science.shtml .
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