Why Do Moving Objects Slow Down?: A Look at Friction

By: Jennifer Boothroyd
Publisher: Lerner Classroom
Publication Date: August 2010
ISBN: 978-0761360575
Reviewed by: Deb Fowler
Review Date: September 2010

When a baseball player slides into home his cleats rub against the ground and create friction, “a force created by rubbing.” When friction is created, it can make things slow down or make them stop totally. For example, when you push a toy car across the floor it will eventually slow down and stop because of the friction created when the “wheels rub on the floor.” If there wasn’t any friction created, the car would keep on rolling. Some surfaces are much bumpier than others and “make a lot of force.” If you took that same toy car that rolled quickly across a floor and tried to roll it across a carpet, it wouldn’t go very far because a carpet creates a lot more friction. If you go ice skating you know how difficult it can be to stop because the surface of the ice has “few bumps and grooves.”

Some surfaces such as a goldfish bowl don’t appear to have any bumps or grooves, but “every surface makes some amount of friction.” Water and air also create friction. In this book you can see a dolphin creating fiction as he swims through the water and a parachute creating friction as it drifts down to earth. There doesn’t appear to be any friction in air, but “Air is made of gases” and “Friction in the air is called air resistance.” In this book you will learn about how the weight of an object can affect the amount of friction felt, how friction can help us, you’ll see examples of “good" friction, you’ll see examples of “bad” friction, the problems bad friction can cause, and you’ll learn about lubrication and how it “can reduce friction.”

This book gives an excellent overview of the basic physics of friction and identifies different types of forces. Physical science can be fun and interesting and the text and examples in this book make the concepts very easy to understand. Each concept is accompanied by a short, easily understood explanation and a visual photographic example. For example, when discussing why a boat can go fast in the water, it states, “The outside of a boat is smooth. A smooth boat makes little friction in the water.” The photograph shows a high performance speed boat easily moving across the water. In the back of the book is a hands-on activity, “Get a Grip,” an index, a glossary, and additional recommended book and website resources.

Quill says: If you are interested in introducing very basic physics concepts in your classroom, this series, Exploring Physical Science, will prove to be an excellent resource!