Bobby Mercer - Junk Drawer Physics: 50 Awesome Experiments That Dont Cost a Thing

Copyright 2014 by Bobby Mercer

All rights reserved

First edition

Published by Chicago Review Press, Incorporated

814 North Franklin Street

Chicago, Illinois 60610

ISBN 978-1-61374-920-3

Library of Congress Cataloging-in-Publication Data

Mercer, Bobby, 1961- author.

Junk drawer physics : 50 awesome experiments that dont cost a thing / Bobby Mercer. First edition.

pages cm

Audience: 9+

ISBN 978-1-61374-920-3 (trade paper)

1. PhysicsExperimentsJuvenile literature. I. Title.

QC25.M35 2014

530.078dc23

2013046726

Cover design and art: Andrew Brozyna, AJB Design, Inc.

Interior design: Rattray Design

Printed in the United States of America

5 4 3 2 1

To Jordan and Nicole, I hope you always enjoy the wonder of why.

B ooks dont happen without great people. Thanks to all the people who helped turn the idea for Junk Drawer Physics into this book: Kathy Green for being a great agent. Jerome Pohlen, Amelia Estrich, and the creative people at Chicago Review Press for making it look great. Thanks to my wonderful family. Michele, you are amazing and understanding when I dont put the glue back. Nicole, for helping me build most of the activities this book. Jordan, thanks for making us all smile. A special thanks to Team Science: Jennifer Allsbrook, Shannon Haynes, Kim Mirasola, Laura Spinks, and Sergey Zalevskiy.

W e all have a junk drawer containing the odds and ends that we accumulate as we go through life. In the pages of this book, you will find out that all that junk can help teach you science. The fun projects in this book will use inexpensive or no-cost objects. Most of it is stuff you probably already have.

Hands-on science is entertaining for everybodyfun for kids from 5 to 85. Enjoy yourself, be careful, and you just might learn something.

Turn an old CD into a mind-bending tabletop spinner. Spin, stare, and watch the world change.

Adult supervision required

Old CD

Paper

Markers

Scissors

Superglue or hot glue

2 flat glass beads

Step 1: Trace around a CD on a piece of paper. Use a marker to create swirls going out from the center, as shown. Then cut around the outside of the CD line.

Step 2: You need adult permission or help for this step. Lay a piece of scrap paper on your work surface to catch any glue that drips. Use hot glue or superglue to affix the round piece of paper to the CD. Then glue one glass bead to each side of the hole in the center of the CD, with the flat sides facing the hole. These glass beads are commonly found in craft stores and are used as decorations for flower vases, tabletop water fountains, and candle sets. Let the glue dry completely.

Step 3: If you color in the swirls, it will make them wider, which will make the illusion better.

Step 4: Pinch the top glass bead with your fingers and spin it. Practice until you can get it to spin like a top while sitting in place.

Step 5: Now spin the top and lean directly over it. Stare at the center for about 30 seconds as it spins, then look up at a plain wall. It should make the wall spin a little bit. Keep practicing until you master it.

Try staring at the top for different amounts of time. Crazy! Do it again and look at other things. Amaze your friends as you warp the world around you. You can make other tops and try different patterns and colors.

The spiral on the top of the CD trains your eyes to follow the swirl. This effect is called persistence of vision. Your brain holds onto an image for a fraction of a second. Since that image is a spinning spiral, when you look at a wall or something else, it will spiral for a few seconds. It might take a few tries to get good at it. (Even if you dont always get the swirl effect, you still made a fun top.)

Use a piece of paper to learn about inertia.

Several strips of paper

Scissors

Coins

Tape

Step 1: For this experiment, you need several strips of paper. A long grocery list notepad will work, or you can take a sheet of letter size paper and cut it into four strips. Paper that is already written on is perfectyoure recycling.

In each strip, make two cuts that almost go through the paper, as shown. To do this, fold each strip of paper, but do not crease the center. This will insure the cuts are equal in length.

Step 2: Pick up a single strip, holding one end in each hand. Your goal is to try to tear both ends off at the same time so that you are left with just the center part. First, pull slowly and watch what happens. Then repeat with another strip and try pulling faster. Can you do it?

Step 3: Now tape four or five coins to the center section of a cut strip.