Home Run! Science Projects with Baseball and Softball by Robert L. Bonnet

Author:Robert L. Bonnet [, ]
Language: eng
Format: epub
ISBN: 978-1-4645-0667-3
Publisher: Enslow Publishers, Inc.
Published: 2010-10-14T16:00:00+00:00

EXPERIMENT 4.1

How Do Shoes Affect a Runner's Speed?

MATERIALS

several friends

pair of flat-bottom shoes and a pair of shoes with cleats for each friend

stopwatch

ball field or area where someone can run a straight 90-foot path

pencil and paper

Traction is the amount of friction between an object and the surface upon which it is moving. When running, it is desirable to have as much traction as possible. Have you ever tried to run fast on beach sand? You know it is harder than running on a concrete sidewalk. There is more friction between your shoes and solid concrete than between your shoes and shifting sand.

To increase traction when running on dirt or grass, many people playing sports such as soccer, track, and baseball or softball wear shoes with cleats (see Figure 9). Cleats are studs on the bottom of shoes to assist in gripping the ground. Shoes with cleats help prevent slipping when running, and help give quicker starts. Cleats have better traction because the force of the runner’s body weight is concentrated into the small, pointed surfaces of the many cleats on the shoes, instead of being spread out over the flat bottom of a shoe. Once all those points are firmly in the ground, there is more surface area in contact with the ground. Since the key to friction is how much surface area is in contact with another surface, cleats give a better grip.

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