learning about forces and motion

Students know an object’s motion can be described by recording the change in position of the object over time.. Students know the way to change how something is moving is by giving i

Genre Comprehension Skill Text Features Science Content

Nonfi ction Cause and Effect • Captions

• Labels

• Glossary

Forces and Motion

Scott Foresman Science 2.1

Standards Preview

Standard Set 1 Physical Sciences

1 The motion of objects can be

observed and measured As a basis for

understanding this concept:

1.a Students know the position of an

object can be described by locating it

in relation to another object or to the

background.

1.b Students know an object’s

motion can be described by

recording the change in position of

the object over time.

1.c Students know the way to change

how something is moving is by giving it

a push or a pull The size of the change is related to the strength, or the amount of force, of the push or pull.

1.d Students know tools and machines

are used to apply pushes and pulls (forces) to make things move.

1.e Students know objects fall to

the ground unless something holds them up.

1.f Students know magnets can be

used to make some objects move without being touched.

ISBN 0-328-23495-8

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by Kristin Cashore

Physical Sciences

attract

force

friction

gravity

motion

repel

Picture Credits

Every effort has been made to secure permission and provide appropriate credit for photographic material The

publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions.

Unless otherwise acknowledged, all photographs are the copyright of Dorling Kindersley, a division of Pearson.

Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd).

4 Getty Images; 13 Jerry Young/DK Images.

ISBN: 0-328-23495-8

Copyright © Pearson Education, Inc All Rights Reserved Printed in the United States of America

This publication is protected by Copyright, and permission should be obtained from the publisher prior to any

prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic,

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Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.

1 2 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06

by Kristin Cashore

Learning About

Position

Position is where an object is How can you

talk about position? You can use words such as

behind and in front of to talk about position.

Look at the picture of the man and the girl

The man is behind the counter The girl is in

front of the counter.

The water is to the

left of the fruit The

woman is behind the

counter.

3

You can also use words such as left and right

to talk about position Do you see the water on

the counter? It is to the left of the fruit How can you use left and right to talk about the fruit?

How else can you talk about position? You

can talk about position based on something

that does not move The background does not

change The cabinets and stove do not move

They are in the background of the picture

Things in the

background can help

you talk about position.

5

We measure things to learn more about position Look at the fl owers and lemons in the picture below Their positions can be measured

The fl owers are 1 meter from the sink The lemons are 11 centimeters from the fl owers

Use meters and centimeters to

11 centimeters

Learning About

Motion

Motion is the act of moving In what way

do things move? Some things move back and

forth Some things move around and around

Some things move in a straight line

The boy in the picture moves back and forth

on the swing The top spins around and around

Your car moves in a straight line

The cars move

in a straight

line.

The boy swings back and forth.

The top spins around and around.

7

The speed of motion can change If the boy moves his legs more quickly, he will run faster

The direction of motion can change If the boy on the bicycle turns the handlebars, the bicycle changes direction

Things move at different speeds Look at the picture The boy ran for 10 seconds The other

boy pedaled for 10 seconds Who do you think

went faster? Who do you think went farther?

The bicycler traveled faster and farther than the runner

Force

An object needs a push or pull to move A

push or pull that can make something move is

called a force.

An object will move in the same direction it

is pushed or pulled It will not speed up or slow

down until it is given another push or pull

The more force you use,

the farther the box will go!

9

Pushing a wagon gently takes little force

Pushing it harder takes more force The cart moves farther when you push it harder! It takes more force to move objects farther

It takes more force to move a heavy thing than a light thing Which wagon takes more force to move? Read the caption to fi nd out!

It takes more force to move the wagon with the black dog.

Learning About

Friction

What if you give a cart a push and let it go?

After a while, it stops moving This is because

of friction.

Friction is a kind of pull It makes a moving

object slow down or stop The carts slow down

because of friction between them and the

ground

The girl works against

friction to push the carts.

11

Look at the skaters The one on the smooth road goes faster than the one on the sand

There is a lot of friction between the skates and the sand This friction makes the skates slow down There is less friction between the skates and the road This allows the skater to go faster

on the road.

The skater moves fast on the road.

The skater moves slowly on the sand.

Learning About

Tools and Machines

How do tools and machines help us? Tools

and machines use pushes and pulls to make

things move Tools and machines can help us

do hard things!

A hammer is a tool It

uses force to drive in

the nail.

13

See the picture? A wooden spoon is a tool It pushes the food It helps mix the eggs and fl our

A truck is a machine Its engine uses force

The force spins the truck’s wheels Then it can move the heavy logs

A truck is a machine A truck helps us move heavy things.

The spoon helps mix the meal It is a tool.

Learning About

Gravity

Look at the picture The boy is shooting the

ball What will happen? Will the ball fl oat into

the sky? Will it land on the ground?

Gravity will pull the ball down to the

ground What is gravity? Gravity is a pulling

force It pulls things toward Earth’s center

When you jump up, you come back down

Gravity is what makes you come back down

Gravity pulls the ball

toward the center of

Earth.

15

What does it mean if something is heavy? It means the pull of gravity on that thing is strong

Gravity pulls harder on heavier things

The ball weighs more than the apple Gravity pulls harder on the ball than on the apple

Gravity pulls harder on heavy things than on light things.

Learning About

Magnets

What is a magnet? A magnet is a special

object that creates a force Magnets can push

some kinds of metal

The letters and numbers on the refrigerator door are magnets.

17

Magnets attract some metal objects To

attract is to pull toward Look at the picture

The paper clips are made of metal The magnet attracts them

Magnets can attract or repel other magnets

To repel is to push away

This magnet has attracted several paper clips.

Magnets have poles The pole is the part of

the magnet that has the strongest push or pull

Look at the magnets in the picture The north

pole is marked with an N The south pole is

marked with an S Each magnet has a north

pole and a south pole

The N and S on a magnet show where its poles are.

19

Opposite poles attract each other Like poles repel each other

Magnets can move some objects without touching them Look at the picture The magnet

is not touching the lock But the magnet is pulling the lock!

The magnet attracts the metal of the lock without touching it.

attract pull toward

force a push or a pull that makes

something move

friction a pull that makes a moving

object slow down or stop moving

gravity a force that pulls things toward

the center of Earth

motion the act of moving

repel push away

Glossary What did you learn?

1 What will happen if you put the like poles of

two magnets together?

2 Does gravity pull harder on a bowling ball or

a feather? How do you know?

3 Look at the classroom around you Think about position Write to explain the position of at least two things in

the classroom Use words such as behind, in

front of, left, right, or background

4 Cause and Effect You throw a ball into

the air What caused it to move? What effect does gravity have on the ball?