Cindy Blobaum - Explore Gravity!: With 25 Great Projects

Newest titles in the Explore Your World! Series

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Copyright 2013 by Nomad Press. All rights reserved.

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ISBN: 978-1-61930-207-5

Illustrations by Bryan Stone

Educational Consultant, Marla Conn

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We elected to print Explore Gravity! With 25 Great Projects on paper containing 100% post consumer waste.

Index

Wherever you are right now, point a finger straight down. Change your position and point straight down. Stand up. Stand on your head. Lie down. Did you point to the same spot? How do you know which way is down?

These questions may seem simple, or even silly. Of course you know which way is down. Down means toward the ground. When you are standing, down means toward your feet. If you stand on your head, down means below your head. If you are sitting in a desk chair, down goes by your side.

WORDS KNOW

down: toward the ground. If youre underground, down means toward the center of the earth.

On the earth, the force of gravity pulls everything toward its center. There are forces pushing and pulling objects all the time. Wind pushes tree branches and sailboats. Your muscles push and pull parts of your body so you can walk, talk, and move.

You can see some forces, but you cant see gravity. Its invisible. You can choose to use many forces, but gravity is different. You cant turn it on or off. It pulls you down whether you want it to or not. Without it, you would float away!

How does gravity keep you safe? Why does the position of your belly button matter? How do astronauts work in zero gravity? Can gravity make life easier? Youll learn the answers to these questions and more in this book!

WORDS KNOW

force: a push or a pull.

gravity: a natural force that pulls objects to the earth.

object: something that can be seen or touched.

invisible: unable to be seen.

astronaut: a person who travels or works in space, where the moon, sun, planets, and stars are.

matter: something real that takes up space.

scientist: someone who studies science and asks questions about the natural world, seeking answers based on facts.

Gravity works on all matter. Matter is the word scientists use to describe anything that takes up space. You can measure matter, even though sometimes you cant see it or touch it. Water is matter, and so is air and gases.

Chocolate cake is matter. It takes up space. You can stick a fork in it, and describe how it looks and tastes. A feather is matter, and so are dogs and cats, a car, this book, your body, and even a speck of dust.

Gravitys force is a natural attraction that affects all matter. Gravity pulls all matter closer together. There is gravity between an apple and a banana sitting on a table. There is gravity between a bird and a tree. Most of the time, the pull of gravity between objects is so small that we dont notice it. But the more matter an object has, the stronger its pull.

WORDS KNOW

attraction: an invisible power that pulls things together.

gravitational pull: the force of gravity acting on an object.

The earth is very, very big. Its gravitational pull is stronger than anything else around it. Earths gravity pulls you, the air, plants, trees, and even the moon, closer to its center. It keeps our feet on the ground!

What isnt matter? Your thoughts and feelings. They are real, but they dont take up space. You cant touch or measure them. Gravity isnt matter. It doesnt take up space and you cant touch it.

Did You Know?

The suns gravity is pulling at you, but its so far away you dont notice it. Earth is by far the biggest, closest object to humans, so it has the strongest pull on us.

A science journal is a great place to note the steps of your experiments, make observations, and record data. A scientific method worksheet is a useful tool for keeping your ideas and observations organized. The scientific method is the way scientists ask questions, form a hypothesis, and then find answers.

WORDS KNOW

observation: something you discover using your senses.

data: a collection of facts.

hypothesis: a prediction or unproven idea that tries to explain certain facts or observations.

SUPPLIES

• plain paper
• stapler
• markers
• pencil

Stack about five sheets of paper and fold them in half.

Staple along the folded edge about 1 inch in (2 centimeters) to secure the pages together.

Decorate the cover any way you want. Just dont forget the word