Steven Holzner - Physics I For Dummies

In writing this book, we made some assumptions about you:

You have no or very little prior knowledge of physics.

You have some math prowess. In particular, you know algebra and a little trigonometry. You don’t need to be an algebra pro, but you should know how to move items from one side of an equation to another and how to solve for values.

You want physics concepts explained clearly and concisely, and you want examples that let you see those concepts in action.

The natural world is, well, big. And to handle it, physics breaks the world down into different parts. The following sections present the various parts you see in this book.

You usually start your physics journey with motion, because describing motion — including acceleration, velocity, and displacement — isn’t very difficult. You have only a few equations to deal with, and you can get them under your belt in no time at all. Examining motion is a great way to understand how physics works, both in measuring and in predicting what’s going on.

“For every action, there is an equal and opposite reaction.” Ever heard that one? The law (and its accompanying implications) comes up in this part. Without forces, the motion of objects wouldn’t change at all, which would make for a very boring world. Thanks to Sir Isaac Newton, physics is particularly good at explaining what happens when you apply forces. You also take a look at the motion of fluids.

If you apply a force to an object, moving it around and making it go faster, what are you really doing? You’re doing work, and that work becomes the kinetic energy of that object. Together, work and energy explain a whole lot about the whirling world around you, which is why we dedicate Part 3to these topics.

What happens when you stick your finger in a candle flame and hold it there? You get a burned finger, that’s what. And you complete an experiment in heat transfer, one of the topics you see in Part 4, which is a roundup of thermodynamics — the physics of heat and heat flow. You also see how heat-based engines work, how ice melts, how the ideal gas behaves, and more.

The Parts of Tens is made up of fast-paced lists of ten items each. You discover all kinds of amazing topics here, like some far-out physics — everything from black holes and the Big Bang to wormholes in space — as well as some famous scientists whose contributions made a big difference in the field.

You come across some icons that call attention to certain tidbits of information in this book. Here’s what the icons mean:

This icon marks information to remember, such as an application of a law of physics or a particularly juicy equation.

When you run across this icon, be prepared to find a shortcut in the math or info designed to help you understand a topic better.

This icon highlights common mistakes people make when studying physics and solving problems.

This icon means that the info is technical, insider stuff. You don’t have to read it if you don’t want to, but if you want to become a physics pro (and who doesn’t?), take a look.

In addition to what you’re reading right now, this book comes with a free access-anywhere Cheat Sheet for when you need a quick physics refresher on important constants and equations. To get this Cheat Sheet, simply go to www.dummies.com and type Physics I For Dummies Cheat Sheetin the search box.

You can leaf through this book; you don’t have to read it from beginning to end. Like other For Dummies books, this one was designed to let you skip around as you like. This is your book, and physics is your oyster. You can jump into Chapter 1, which is where all the action starts; you can head to Chapter 2for a discussion of the necessary algebra and trig you should know; or you can jump in anywhere you like if you know exactly what topic you want to study. And when you’re ready for more-advanced topics, from electromagnetism to relativity to nuclear physics, you can check out Physics II For Dummies .

Part 1

IN THIS PART …

Part 1 is designed to give you an introduction to the ways of physics. Motion is one of the easiest physics topics to work with, and you can become a motion meister with just a few equations. This part also arms you with foundational info on math and measurement to show how physics equations describe the world around you. Just plug in the numbers, and you can make calculations that astound your peers.

Chapter 1

IN THIS CHAPTER

Recognizing the physics in your world

Understanding motion

Handling the force and energy around you

Getting hot under the collar with thermodynamics

Physics is the study of the world and universe around you. Luckily, the behavior of the matter and energy — the stuff of this universe — is not completely unruly. Instead, it strictly obeys laws, which physicists are gradually revealing through the careful application of the scientific method, which relies on experimental evidence and sound rigorous reasoning. In this way, physicists have been uncovering more and more of the beauty that lies at the heart of the workings of the universe, from the infinitely small to the mind-bogglingly large.

Physics is an all-encompassing science. You can study various aspects of the natural world (in fact, the word physics is derived from the Greek word physika, which means “natural things”), and accordingly, you can study different fields in physics: the physics of objects in motion, of energy, of forces, of gases, of heat and temperature, and so on. You enjoy the study of all these topics and many more in this book. In this chapter, we give an overview of physics — what it is, what it deals with, and why mathematical calculations are important to it — to get you started.

Many people are a little on edge when they think about physics. For them, the subject seems like some highbrow topic that pulls numbers and rules out of thin air. But the truth is that physics exists to help you make sense of the world. Physics is a human adventure, undertaken on behalf of everyone, into the way the world works.