0.0 - Welcome to an electronic physics textbook!
Textbooks, like this one, contain words and illustrations. In an ordinary textbook, the
words are printed and the illustrations are static, but in this book, many of the
illustrations are animations and many words are spoken. Altogether, this textbook
contains more than 600,000 words, 150 simulations, 1000 animations, 5000
illustrations, 15 hours of audio narration, and 35,000 lines of Java and JavaScript
code.
All this is designed so that you will experience more physics. You will race cars
around curves, see the forces between charged particles, dock a space craft,
generate electricity by moving a wire through a magnetic field, control waves in a
string to “make music”, measure the force exerted by an electric field, and much
more. These simulations and animations are designed to allow you to “see” more
physics and make it easier for you to assess your learning, since many of them
pose problems for you to solve.
The foundation of this textbook is the same as a traditional textbook: text like this
and illustrations. Concepts like “velocity” or “Newton’s second law” are explained as
they are in traditional textbooks. From there we go a step further, taking advantage
of the computer and giving you additional ways to learn about physics. The textbook
has many features: simulations; problems where the computer checks your answers
and then works with you step by step; animations that are narrated; search
capability; and much more. We will start with some simulations. In subsequent
sections, we will show you how we use animations and narration to teach physics,
and how a computer will help you solve problems.
At the right are three examples of how we take advantage of an interactive
simulation engine. Click on any of the illustrations to start an interactive simulation; it
will open a separate window. When you are done, you can close the window. The
window that contains this text will remain open.
In the first simulation, you aim the monkey’s banana bazooka so that the banana
will reach the professor. The instant the banana is fired, the professor lets go of the
tree and falls toward the ground. You aim the banana bazooka by dragging the
head of the arrow shown on the right. Aim the bazooka and then press GO. Press
RESET to try again. (And do not worry: We, too, value physics professors, so the
professor will emerge unscathed.)
This is an animated version of a classic physics problem and appears about halfway
through a chapter of the textbook. The majority of our simulations require the
calculation of precise answers, but like this one, they are all great ways to see a
concept at work.
In the second simulation, you can extend a simple circuit. The initial circuit shown
on the right contains a battery and a light bulb. You can add light bulbs or more wire
segments by dragging them near the desired location. Once there, they will snap
into place. You can also use an ammeter to measure the amount of current flowing
through a section of a wire, and a voltmeter to measure the potential difference
across a light bulb or the battery.
There are many experiments you can conduct with these simple tools. For instance,
place a light bulb in the horizontal segment above the one which already contains
the light bulb and connect it to the circuit with two additional vertical wire segments.
Does this alter the power flowing through the first light bulb? The brightness of each
light bulb is roughly proportional to the power the circuit supplies to it.
How do the potential differences across the light bulbs compare to one another? To the potential difference across the battery? Measure the
current flowing through a piece of wire immediately adjacent to the battery, and through each of the wire segments that contains a light bulb.
Do you see a mathematical relationship between these three values?
You will be asked to make observations in many simulations like this, and as you learn physics, to apply what you have learned to answer
problems posed by the simulations. You will use your knowledge to do everything from juggle to dock a spaceship!
In the third simulation, you experiment with a simple electric generator. When the crank is turned, the rectangular wire loop shown in the
illustration turns in a magnetic field. The straight lines you see are called magnetic field lines. Turning the handle of the generator creates an
electric current and what is called an emf. The emf is measured in volts.
After you launch the simulation, you can change your point-of-view with a slider. The illustration you see to the right provides a conceptual
overview of what a generator is. If you change the viewing angle, you can better see the angle between the wire and the field, and how that
affects the current. A device called an oscilloscope is used to measure the emf created by the generator.