Table Of Content

Childcraft THE HOW AND WHY LIBRARY VOLUME 12 How Things World Book. Inc. aScottFetzercompany Chicago London Sydney Toronto ) 1992 Editi—on Childcraft The How and WhyLibrary (Reg.US,Pat.Ofl !E 1991WorldBook,Inc,Allrightsreserved,Ttiis volumemaynotbereproducedinwholeorinpartinany formwithoutpriorwrittenpermissionfromthepublisher. WorldBook,Inc 525WestMonroe Chicago,IL60661 (ci1990,1989.1987.1986,1985byWorldBook,Inc i 1982,1981, 1980,1979US.A byWorldBook-ChildcrallInternational,Inc S 1976,1974.1973,1971, 1970,1969.1968.1965,1964U.S.A.by FieldEnterprisesEducationalCorporation InternationalCopynghl { 1987,1986,1985byWorldBook,Inc InternationalCopyright c 1982, 1981.1980.1979byWorldBook- ChildcraftInternational,Inc. InternationalCopyright e 1976.1974.1973.1971,1970.1969.1968, 1965.1964byFieldEnterprisesEducationalCorporation. ISBN0-7166-0191-5 LibraryofCongressCatalogCardNumber90-70178 PrintedintheUnitedStatesofAmerica A/IB Acknowledgments Thepublishersol Childcraft—The Howand WhyLibrary gratefullyacknowledgethecourtesyofthefollowing publishers, agencies, and corporationsforpermissionto usecopyrighted stories, poems, andothermatenal inthisvolume Full Illustrationacknowledgments appearonpages313-314. CricketIvlagazine: Thewindskippertoyadaptedfrom Cricket Magazine Houghton Mifflin Company: I Met aMan I Could NotSee."from/ Meta Man byJohn Ciardi. published by Houghton fvliftim Company. Copynght6 1961 byJohnCiardi. Repnnted bypermission Western Publishing Company, Inc "Hump, the Escalator by DorothyFaubion Copyright 1942 by Story Parade, Inc Reprinted by permissionofWestern PublishingCompany, Inc. — Volume 12 How Things Work Contents 5 Let's Get Moving It takes a push or pull to get things moving or to make them stop. 23 Full of Energy Sunlight, wind, and burning coal are just a few of the forms of energy that make things work. 57 Machines Make Easy It Not all machines are complicated. Some very simple machines help people get things done. 99 What's the Matter? You and ever\1;hing around you are made of tiny bits of matter called atoms and molecules. 121 Hot and Cold When heat energj- spreads, things get warmer or cooler. 161 Seeing the Light Because light bounces and bends, you can see the shape, size, and color of things around you. 21 1 Currents and Sparks Electricity traveling through a wire makes things hght up, heat up, or move. 239 Hear All About It Every sound you hear is a vibration made by something that is moving. 287 More Things That Work — From microwave ovens to motion pictures here is how some familiar things work. 306 Books to Read 308 New Words 312 Illustration Acknowledgments 314 Index / ^ ^ Pushes and pulls Back and forth, up and down. Swinging in a swing is almost like flying. What makes the swing go up in the air? Most of the time you do. You "pump" with your legs and body. Sometimes you can get a friend to push you. And sometimes you see the empty swing moving when the wind — pushes it. But something you, your friend, — or the wind has to give it a push. The swing can't move by itself. Anytime a thing moves, something makes move. Something pushes the way you, it it, your friend, or the wind pushes the swing. Or something pulls it, the way you pull a wagon or a sled. The push or the pull that makes a thing move is called a force.