Level: N Word Count: 331 100th Word: planets (page 8) Teaching Focus: Phonics: Word Study Look at the words float and plants. How are the words alike? How are they different? Tips on Reading This Book with Children: 1. Read the title. Predictions after reading the title have children make predictions about the book. 2. Take a book walk. Talk about the pictures in the book. Use the content words from the book as you take the picture walk. Have children find one or two words they know as they do a picture walk. 3. Have children find words they recognize in the text. 4. Have children read the remaining text aloud. 5. Strategy Talk use to assist children while reading. Get your mouth ready Look at the picture Think does it make sense Think does it look right Think does it sound right Chunk it by looking for a part you know 6. Read it again. 7. Complete the activities at the end of the book.
Gravity! Do You Feel It? by Buffy Silverman Science Content Editor: Kristi Lew www.rourkeclassroom.com
Science content editor: Kristi Lew A former high school teacher with a background in biochemistry and more than 10 years of experience in cytogenetic laboratories, Kristi Lew specializes in taking complex scientific information and making it fun and interesting for scientists and non-scientists alike. She is the author of more than 20 science books for children and teachers. 2012 Rourke Publishing LLC All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical including photocopying, recording, or by any information storage and retrieval system without permission in writing from the publisher. www.rourkeclassroom.com Photo credits: Cover mountainpix, Cover logo frog Eric Pohl, test tube Sergey Lazarev; Table Of Contents & Page 4 Phase- 4Photography; Page 5 Kadroff; Page 7 greenland; Page 9 Racheal Grazias; Page 10 Steve Collender; Page 11 Richard Susanto; Page 13 Monkey Business Images; Page 14 TRINACRIA PHOTO, jackhollingsworthcom, LLC; Page 16 Matamu; Page 15 Peter Hansen; Page 17 Orla; Page 19 paul prescott; Page 21 oorka Editor: Kelli Hicks Cover and page design by Nicola Stratford, bdpublishing.com Library of Congress Cataloging-in-Publication Data Silverman, Buffy. Gravity! do you feel it? / Buffy Silverman. p. cm. -- (My science library) Includes bibliographical references and index. ISBN 978-1-61741-754-2 (Hard cover) (alk. paper) ISBN 978-1-61741-956-0 (Soft cover) 1. Gravity--Juvenile literature. I. Title. II. Series. QC178.S467 2012 531.14--dc22 Rourke Publishing Printed in China, Power Printing Company Ltd Guangdong Province 042011 042011LP 2011004841 www.rourkeclassroom.com - rourke@rourkepublishing.com Post Office Box 643328 Vero Beach, Florida 32964
Table of Contents What Is Gravity? 4 How Does Gravity Work? 10 Orbiting in Space 16 Show What You Know 22 Glossary 23 Index 24
What Is Gravity? Toss a ball into the sky. No matter how hard you throw it, the ball comes back to the ground. What makes the ball return to Earth? Gravity! 4
You cannot see gravity. But, you can see that it pulls a ball back to Earth. 5
Gravity is a force. A force is something that pushes or pulls an object. The Earth s gravity pulls objects towards the center of the Earth. What would happen if there was no gravity? Rocks, houses, plants, and animals would float into space. People would float, too. You have to work hard to climb up a climbing wall because gravity is pulling. 6
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8 The force of gravity pulls all objects towards each other. Every object in the universe pulls on every other object. The Earth, Sun, Moon, and planets pull on each other. Buildings, cars, and trains pull on each other. You have gravitational pull, too!
A rollercoaster zooms down a track. Gravity pulls on it as it goes up and down. 9
How Does Gravity Work? Everything in the universe is made of matter. People, air, water, rocks, and planets are made of matter. Scientists call the amount of matter in an object its mass. The air inside these balloons is a type of matter. Matter is anything that has mass and takes up space. 10
A tree has more mass than you! 11
Objects with more mass have more gravitational pull. The Earth has much more mass than you do. That means that the Earth pulls with more force. The force of the Earth s gravity keeps you on Earth. 12
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Your weight is a measure of the pull of gravity between you and the Earth. The Moon is smaller than Earth and has less mass. That means that its gravity has less pull. A 70-pound (32 kilograms) child weighs only 12 pounds (5 kilograms) on the Moon. On Earth I weigh 70 pounds or 32 kilograms. On the Moon I weigh 12 pounds or 5 kilograms. 14
When astronauts went to the Moon, they weighed less than on Earth. 15
Orbiting in Space Objects in space pull each other together. The Sun has much more mass than the Earth. Its gravity is stronger. The Sun has a greater pull than Earth. It holds the Earth in place as the Earth moves in an orbit around the Sun. 16 The Sun makes up 99.86% of the mass of the solar system. It pulls on all the planets. The planets orbit the Sun.
The Sun s gravity holds the planets in the solar system. Earth Sun 17
The Earth has more mass than the Moon. Its gravity is stronger. The Earth s gravity pulls more than the Moon s gravity. The Moon orbits the Earth. It cannot escape Earth s gravity. Gravity pulls the Earth and Moon together. 18
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20 The force of gravity also depends on the distance between two objects. Planets that are far apart have less pull on each other. Imagine traveling far from any moons, planets, or stars. There would be almost no gravity pulling on you. Then you could float away!
Mars Moon Earth Mars is farther from Earth than the Moon. There is less gravitational pull between Mars and Earth. 21
1. What would happen if the Earth had no gravity? 2. Why is there less gravity on the Moon than on Earth? 3. How would your weight change if you visited a planet with more mass than Earth? 22
Glossary force (FORS): something that pulls or pushes something else gravitational pull (GRAV-uh-TA-shun-ul PULL): the force that pulls objects together gravity (GRAV-uh-tee): a force that pulls matter together mass (MASS): the amount of matter that an object contains matter (MAT-ur): anything that has mass and takes up space orbit (OR-bit): the path of an object as it revolves around a planet or sun planets (PLAN-its): large bodies, such as Earth, that revolve around a star universe (YOO-nih-vurss): the Earth, planets, stars, and all things that exist in space weight (WATE): a measure of the pull of gravity between an object and Earth or another planet 23
Index Earth(s) 4, 5, 6, 8, 12, 14, 15, 16, 17, 18, 19, 21 force 6, 8, 12, 20 gravity 4, 6, 8, 14, 16, 18, 20 matter 4, 10 mass 10, 11, 12, 14, 16, 18 Moon(s) 8, 14, 15, 18, 20, 21 orbit(s) 16, 18 planet(s) 8, 10, 16, 17, 20 Sun(s) 8, 16, 17 weight 14 Websites www.exploratorium.edu/ronh/weight/index.html www.historyforkids.org/scienceforkids/physics/space/gravity.htm www.primarygames.com/arcade/gravity/start.htm www.sciencenetlinks.com/interactives/gravity.html About the Author Buffy Silverman tries to beat gravity when she hikes and bicycles. When she s not exploring the great outdoors, she writes about science and nature. 24
Comprehension & Extension: Summarize: What is gravity? How does gravity affect people and the Earth? Text to Self Connection: Would you like to travel to space? What do you think it would feel like to be in no gravity? Extension: Write a Narrative Use the factual information from the book to help you write a fiction story about traveling in space. Sight Words I Used: other that towards what would Vocabulary Check: Use glossary words in a sentence.
Have you ever wondered about the science all around us? Plants grow and change, the Sun rises to warm the Earth, and matter changes from one form to another. Investigate Life, Physical, Earth, and Technology science topics with Rourke s My Science Library. This library explores NSTA science standards with engaging text and colorful images to support readers from kindergarten to third grade. Are you ready to investigate? Books in My Science Library: Earth is Tilting! Gravity! Do You Feel It? Let s Classify Animals! Melting Matter Natural or Man-Made? Plants Make Their Own Food Seeds, Bees, and Pollen Studying Weather and Climates What Do Critters Do in the Winter? What s on the Food Chain Menu? Where Did the Water Go? Zap! It s Electricity! Printed in China www.rourkeclassroom.com