Greg Curran - Homework Helpers: Physics, Revised Edition

Homework Helpers: Physics

GREG
CURRAN

Copyright 2012 by Greg Curran

All rights reserved under the Pan-American and International Copyright Conventions. This book may not be reproduced, in whole or in part, in any form or by any means electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system now known or hereafter invented, without written permission from the publisher, The Career Press.

HOMEWORK HELPERS: PHYSICS
EDITED BY GINA TALUCCI
TYPESET BY EILEEN MUNSON
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I dedicate this second edition to my family,

who collectively make me feel like the luckiest man alive.

My wife, Rosemarie,

supports me in all that I do and makes every aspect of my life easier.

My son, James,

has the courage and confidence to inspire me to believe that anything is possible.

My elder daughter, Amanda,

has a heart so big and full of love that it can be overwhelming.

My younger daughter Jessica,

who looks so much like her mother

and acts so much like her father,

laughs and plays and never takes anything too seriously.

Because of them, my home is my favorite place on Earth!

Once again, I would like to thank Jessica Faust of BookEnds-Inc, who got the Homework Helper series off the ground. Thanks also go out to Eileen Munson, Michael Pye, and the people at Career Press, for making this project possible.

I would also like to thank the following people, in no particular order:

John Haag, who, in addition to being a great friend, was the person who encouraged me to teach physics. It is easy to trace a path of causality back from the publication of this book to his influence on my career path.

Fr. Mickey Corcoran, who helped me a great deal when I started teaching physics.

Matt Distefano, an excellent teacher and the author of Homework Helpers: Biology, who is always there when I need to bounce ideas off someone.

Annette Ferranto, whose babysitting services allowed me to meet my deadline, once again.

Bernard Cornwell, who I dont know personally, but who dispelled the myth of writers block in my mind, for all times.

My father and brother, Peter F. Curran Senior and Junior, for checking the text for errors.

To the entire science department of Fordham Preparatory School, a dedicated and professional group of teachers, colleagues, and friends.

Once again, thank you all!

Physics. Is it a subject for everyone? Or is it only for the so-called geek or nerd who skips the school dance to work on his or her robot? Do you need to love your TI-83 calculator more than your family to really enjoy physics? Consider this: Physics is the study of the laws that govern the universe around us, and because we all live in this universe, arent we all entitled to study these laws? Shouldnt we all have a chance to understand the mysteries of the world around us? Cant we all come to appreciate the implications of these laws in our own way?

It saddens me to think of the many people who avoid taking physics in high school because it has the reputation of being such a hard course. This reputation may be perpetuated by students who do poorly in the subject, after failing to put in the required effort. Some parents who have bad memories of their own experiences in physics class may pass this idea on to their children. This notion may also be reinforced by certain physics teachers who, believing that their subject isnt for everyone, discourage large enrollment in their classes.

I believe that physics is for everyone. Every student should take the opportunity to learn something about this fascinating branch of science. I recognize that everyone has different aptitudes, and physics wont come as easily to some as it will to others, but that doesnt change my opinion. Some students learn the subject quickly and painlessly, with minimal additional support. Other students will struggle with physics, but if they put in the required effort and they are given the additional support that they need, they can still do quite well and learn to enjoy the subject.

Homework Helpers: Physics has been written with the latter type of student in mind. My original intention with this book, as with Homework Helpers: Chemistry before it, is to serve as a sort of private tutor. I laid out the chapters and lessons in an order that should be similar to the order of your lessons in class. If you arent quite getting everything in your physics class, and you want to read additional explanations and try additional problems to build your confidence in the subject, this book can be an invaluable resource. If you want to read up on a subject before your teacher lectures on it, but you find your textbook to hard to follow, give this book a try.

On the other hand, if you have already taken a course in physics and you feel like you could use a refresher, Homework Helpers: Physics can be of service to you as well. You can use this book to brush up on your high school physics before taking a course in college, or before taking the SAT II or AP physics examination.

The important thing is that you give the subject of physics a chance to earn a special place in your heart. Dont be intimidated by things that you have seen or heard about the subject in the past. With the right attitude and effort, you can master the subject, and with knowledge comes appreciation.

Good luck with your studies!

Physics is a skill-based course. Students who begin their study of physics without the appropriate skill base must develop their skills quickly or risk struggling with the course. It is an unfortunate fact that some students fail to learn physics not because of the science, but because of the mathematics required in the course. The best way to keep the frustration level low is to keep the skill level high. In this section, I will quickly identify and review some of the skills and concepts that will help you succeed in physics. For the sake of space, this will represent a brief review, as I want to fill most of these pages with physics rather than basic math.

Like chemistry, physics is a quantitative subject, which uses numbers and units to represent physical quantities. Each number must be recorded with a unit. Otherwise its meaning can be misunderstood. For example, if you read the recorded speed of a car was 45, with no units, you could not be sure of how fast the car was traveling. You might assume that it meant 45 miles per hour, but it could just as easily have been 45 meters per second or 45 kilometers per hour. To avoid confusion, we would record a speed of 45 meters per second as 45 m/s. The sooner that you can get in the habit of recording units with every number, the better. This habit will have a positive effect on your exam scores.