For Beth Hirsch friend forever even when I can’t remember RF Copyright 2012 by Sally M Walker and Roseann Feldmann All rights reserved International copyright secured No part of this book may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording or otherwise without the prior written permission of Lerner Publishing Group Inc except for the inclusion of brief quotations in an acknowledged review Lerner Publications Company A division of Lerner Publishing Group Inc 241 First Avenue North Minneapolis MN 55401 USA For reading levels and more information look up this title at www lernerbooks com Library of Congress Cataloging-in-Publication Data Put screws to the test by Sally M Walker and Roseann Feldmann p cm Searchlight books How do simple machines work Includes index ISBN 978 0 7613 5323 2 lib bdg alk paper ISBN 978 0 7613 8009 2 eBook 1 Screws Juvenile literature I Feldmann Roseann II Title Walker Sally M TJ1338 W35 2012 621 8’82 dc22 2010035552 Manufactured in the United States of America 2 DOC 8 1 14
Contents Chapter 1 WORK page 4 MACHINES page 8 Chapter 2 Chapter 3 Chapter 4 WHAT IS A SCREW page 11 HOW SCREWS HELP US page 19 KINDS OF SCREWS page 29 Chapter 5 (cid:45)(cid:70)(cid:66)(cid:83)(cid:79)(cid:3)(cid:46)(cid:80)(cid:83)(cid:70)(cid:3)(cid:66)(cid:67)(cid:80)(cid:86)(cid:85)(cid:3)(cid:52)(cid:74)(cid:78)(cid:81)(cid:77)(cid:70)(cid:3)(cid:46)(cid:66)(cid:68)(cid:73)(cid:74)(cid:79)(cid:70)(cid:84)(cid:3)(cid:215)(cid:3)(cid:20)(cid:26) (cid:40)(cid:77)(cid:80)(cid:84)(cid:84)(cid:66)(cid:83)(cid:90)(cid:3)(cid:215)(cid:3)(cid:20)(cid:25) (cid:42)(cid:79)(cid:69)(cid:70)(cid:89)(cid:3)(cid:215)(cid:3)(cid:21)(cid:17)
Chapter 1 WORK You work every day At home you work in the kitchen At school you sharpen pencils It may surprise you to learn that you also work during recess and at lunch Playing and eating are work too You do work when you sharpen a pencil Are you working when you play or eat 4
Work Using Force to Move an Object When scientists use the word work they don’t mean the opposite of play Work is using a force to move an object from one place to another Force is a push or a pull You use force to do chores to play and to eat These children are using force to climb a rope ladder 5
