Introduction to SAT II Physics

373 Pages·2006·7.31 MB·English

SATII
PHYSICS
(FROM SPARKNOTES.COM)
Orientation
1.0 Introduction to the SAT II
2.0 Introduction to SAT II Physics
3.0 Strategies for Taking SAT II Physics
SAT II Physics Review
4.0 Vectors
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5.0 Kinematics
6.0 Dynamics
7.0 Work, Energy, and Power
8.0 Special Problems in Mechanics
9.0 Linear Momentum
10.0 Rotational Motion
11.0 Circular Motion and Gravitation
12.0 Thermal Physics
13.0 Electric Forces, Fields, and Potential
14.0 DC Circuits
15.0 Magnetism
16.0 Electromagnetic Induction
17.0 Waves
18.0 Optics
19.0 Modern Physics
20.0 Physics Glossary
Practice Tests
21.0 Practice Tests Are Your Best Friends
Introduction to the SAT II
The SAT II Subject Tests are created and administered by the College Board and the
Educational Testing Service (ETS), the two organizations responsible for producing the
dreaded SAT I (which most people call the SAT). The SAT II Subject Tests were created to
act as complements to the SAT I. Whereas the SAT I tests your critical thinking skills by
asking math and verbal questions, the SAT II Subject Tests examine your knowledge of a
particular subject, such as Writing, U.S. History, Physics, or Biology. The SAT I takes
three hours; the Subject Tests take only one hour.
In our opinion, the SAT II Subject Tests are better tests than the SAT I because they cover
a definitive topic rather than ambiguous critical thinking skills that are difficult to define.
However, just because the SAT II Subject Tests do a better job of testing your knowledge
of a useful subject doesn’t mean the tests are necessarily easier or demand less studying.
A “better” test isn’t necessarily better for you in terms of how easy it will be.
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The Good
• Because SAT II Subject Tests cover specific topics such as Grammar, Chemistry,
and Biology, you can study for them effectively. If you don’t know the structure of
DNA, you can look it up and learn it. The SAT IIs are therefore straightforward
tests: if you know your stuff, you’ll do fine.
• Often, the classes you’ve taken in school have already prepared you well for the
SAT IIs. If you’ve taken a Chemistry class, you’ve probably covered most of the
topics that are tested on the SAT II Chemistry test. All you need is some
refreshing and refocusing, which this book provides.
The Bad
• Because SAT II Subject Tests quiz you on specific knowledge, it is much harder to
“beat” or “outsmart” an SAT II test than it is to outsmart the SAT I. For the SAT I,
you can use all sorts of tricks and strategies to figure out an answer. There are far
fewer strategies to help you on the SAT II. Don’t get us wrong: having test-taking
skills will help you on an SAT II, but knowing the subject will help you much,
much more. In other words, to do well on the SAT II, you can’t just rely on your
quick thinking and intelligence. You need to study.
Colleges and the SAT II Subject Tests
We’re guessing you didn’t sign up to take the SAT II just for the sheer pleasure of it. You
probably want to get into college and know that the only reason for taking this test is that
colleges want or require you to do so.
Colleges care about SAT II Subject Tests for two reasons. First, the tests demonstrate
your interest, knowledge, and skill in specific subjects. Second, because SAT II tests are
standardized, they show how your knowledge of Chemistry (or History or Math)
measures up to that of high school students nationwide. The grades you get in high school
don’t offer such a measurement to colleges: some high schools are more difficult than
others, and students of equal ability might receive different grades, even in classes with a
relatively similar curriculum.
When it comes down to it, colleges like the SAT IIs because the tests make the colleges’
job easier. SAT II tests allow colleges to easily compare you to other applicants and
provide you with an excellent chance to shine. If you got a 93% on your Chemistry final
and a student at another high school across the country got a 91%, colleges don’t know
how to compare the two grades. They don’t know whose class was harder or whose
teacher was a tougher grader. But if you get a 720 on the SAT II Chemistry and that other
kid gets a 650, colleges will recognize the difference in your scores.
College Placement
Occasionally, colleges use SAT II tests to determine placement. For example, if you do
very well on the SAT II Chemistry, you might be exempted from a basic science class. It’s
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worth finding out whether the colleges you’re applying to use the SAT II tests for this
purpose.
Scoring the SAT II Subject Tests
There are three different versions of your SAT II score. The “raw score” is a simple score
of how you did on the test, like the grade you might receive on a normal test in school.
The “percentile score” compares your raw score to all the other raw scores in the country,
letting you know how you did on the test in relation to your peers. The “scaled score,”
which ranges from 200 to 800, compares your score to the scores received by all students
who have ever taken that particular SAT II.
The Raw Score
You will never know your SAT II raw score because it is not included in the score report.
But you should understand how the raw score is calculated because this knowledge can
affect your strategy for approaching the test.
A student’s raw score is based solely on the number of questions that student got right,
wrong, or left blank:
• You earn 1 point for every correct answer
• You lose 1/ of a point for each incorrect answer
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• You receive zero points for each question left blank
Calculating the raw score is easy. Count the number of questions answered correctly and
the number of questions answered incorrectly. Then multiply the number of wrong
answers by 1/ , and subtract this value from the number of right answers.
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raw score = right answers - ( 1/ wrong answers)
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The Percentile Score
A student’s percentile is based on the percentage of the total test takers who received a
lower raw score than he or she did. Let’s say, for example, you had a friend named Gregor
Mendel, and he received a score that placed him in the 93rd percentile. That percentile
tells Gregor that he scored better on the SAT II than 92 percent of the other students who
took the same test; it also means that 7 percent of the students taking that test scored as
well as or better than he did.
The Scaled Score
ETS takes your raw score and uses a formula to turn it into the scaled score of 200 to 800
that you’ve probably heard so much about.
The curve to convert raw scores to scaled scores differs from test to test. For example, a
raw score of 33 on the Biology might scale to a 600, while the same raw score of 33 on the
Chemistry will scale to a 700. In fact, the scaled score can even vary between different
editions of the same test. A raw score of 33 on the February 2004 Math IIC might scale to
a 710, while a 33 in June 2004 might scale to a 690. These differences in scaled scores
exist to accommodate varying levels of difficulty and student performance from year to
year.
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Which SAT II Subject Tests to Take
There are three types of SAT II test: those you must take, those you should take, and
those you shouldn’t take.
• The SAT II tests you must take are those required by the colleges you are
interested in.
• The SAT II tests you should take are tests that aren’t required, but that you’ll do
well on, thereby impressing the colleges looking at your application.
• The SAT II tests you shouldn’t take are those that aren’t required and cover a
subject you don’t feel confident about.
Determining Which SAT II Tests Are Required
You’ll need to do a bit of research to find out if the colleges you’re applying to require that
you take a particular SAT II test. Call the schools you’re interested in, look at their web
sites, or talk to your guidance counselor. Often, colleges require that you take the
following SAT II tests:
• The SAT II Writing test
• One of the two SAT II Math tests (either Math IC or Math IIC)
• Another SAT II in a subject of your choice
The SAT II Chemistry is not usually required by colleges. But taking it and doing well can
show a liberal arts college that you are well-rounded or a science-oriented college that
you are serious about science. In general, it is a good idea to take one science-based SAT
II, such as Biology, Chemistry, or Physics.
Deciding If You Should Take an SAT II That Isn’t Required
There are two rules of thumb for deciding which additional test to take beyond the
Writing and Math tests:
1. Go with what you know. If history is your field, a strong score on the
American History test will impress admissions officers far more than a bold but
mediocre effort on the Physics test.
2. Try to show breadth. Scoring well on similar subject tests such as Math,
Biology, and Chemistry will not be as impressive as good scores in more diverse
subjects, such as Math, Writing, World History, and Biology.
Of course, you also have to know what is considered a good score and whether or not you
can get that score (or higher).
Below we have included a list of the most commonly taken SAT II tests and the average
scaled score on each. If you feel confident that you can get a score that is above the
average (50 points or more), taking the test will probably strengthen your college
application. Please note that if you are planning to attend an elite school, you might have
to score significantly higher than the national average. The following table is just a
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general guideline. It’s a good idea to call the schools that interest you or talk to a guidance
counselor to get a more precise idea of what score you should be shooting for.
Test Average Score
Writing 590–600
Literature 590–600
American History 580–590
World History 570–580
Math IC 580–590
Math IIC 655–665
Biology E&M 590–600
Chemistry 605–615
Physics 635–645
As you decide which test to take, be realistic with yourself. Don’t just assume you’re going
to do great without at least taking a practice test and seeing where you stand.
When to Take an SAT II Subject Test
The best time to take an SAT II Subject Test is right after you’ve finished a year-long class
in that subject. If, for example, you take Chemistry in eleventh grade, then you should
take the SAT II Chemistry near the end of that year, when the material is still fresh in
your mind. (This rule does not apply for the Writing, Literature, and Foreign Language
SAT II tests; it’s best to take those after you’ve had as much study in the area as possible.)
Unless the colleges you’re applying to use the SAT II for placement purposes, there is no
point in taking any SAT II tests after November of your senior year, since you won’t get
your scores back from ETS until after the college application deadline has passed.
ETS usually sets testing dates for SAT II Subject Tests in October, November, December,
January, May, and June. However, not every subject test is administered in each of these
months. To check when the test you want to take is being offered, visit the College Board
Web site at www.collegeboard.com or do some research in your school’s guidance office.
Registering for SAT II Tests
To register for the SAT II test(s) of your choice, you have to fill out some forms and pay a
registration fee. We know, we know—it’s ridiculous that you have to pay for a test that
colleges require you to take in order to make their jobs easier, but, sadly, there isn’t
anything we, or you, can do about it. (It’s acceptable here to grumble about the unfairness
of the world.)
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After grumbling, however, you still have to register. There are two ways to go about it:
online or by mail. To register online, go to www.collegeboard.com. To register by mail, fill out
and send in the forms enclosed in the Registration Bulletin, which should be available in
your high school’s guidance office. You can also request a copy of the Bulletin by calling
the College Board at [phone] or writing to:
College Board SAT Program
P.O. Box 6200
Princeton, NJ 08541–6200
You can register to take up to three SAT II tests for any given testing day. Unfortunately,
even if you decide to take three tests in one day, you’ll still have to pay a separate
registration fee for each.
Introduction to SAT II Physics
THE BEST WAY TO DO WELL ON SAT II Physics is to be really good at physics. For that, there
is no substitute. But the physics whiz who spends the week before SAT II Physics cramming on
Lagrangian mechanics and Dirac notation probably won’t fare any better than the average student
who reviews this book carefully. Why? Because SAT II Physics Tests (and first-year university
courses) do not cover Lagrangian mechanics or Dirac notation. Take this moment to sigh with
relief.
This chapter will tell you precisely what SAT II Physics will test you on, how the test breaks
down, and what format the questions will take. You should read this information carefully and
base your study plan around it. There’s no use spending hours on end studying for stuff that’s not
relevant to the test. Knowing nothing about electromagnetic induction will hurt you on the test,
but nowhere near as much as knowing nothing about optics will.
Content of SAT II Physics
Math and physics go hand in hand, right? You might be surprised, then, to learn that you aren’t
allowed to use a calculator on SAT II Physics. The math required of you never goes beyond simple
arithmetic and manipulation of equations. You have, on average, 48 seconds to answer each
question, and the people at ETS realize that isn’t enough time to delve into problems involving
simultaneous equations or complex trigonometry. They’re more interested in testing your grasp of
the basic concepts of physics. If you’ve grasped these concepts, your weakness in math isn’t going
to hurt you.
ETS breaks down the concepts you need to know for the test into six categories:
Topic Percentage of the Test
Mechanics 34–38%
Electricity and Magnetism 22–26%
Waves 15–19%
Heat, Kinetic Theory, and Thermodynamics 8–12%
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Modern Physics 8–12%
Miscellaneous 2–4%
While these categories are helpful, they are also very broad. You may be a whiz with waves but a
loser with lenses, and want to know how much of the waves portion of the test will be devoted to
optics. To help you out, we’ve broken the test down even further so that you’ll know exactly
where to expect to feel the squeeze. (These figures are only approximations, and may vary from
test to test.)
Topic % of the Test Number of Questions
Mechanics 34–38% 25–29
Vectors 2% 1–2
Kinematics 6% 4–5
Dynamics 10% 7–8
Work, Energy, and Power 6% 4–5
Special Problems in Mechanics 5% 3–4
Linear Momentum 2% 1–2
Rotational Motion 1% 0–1
Circular Motion and Gravitation 4% 2–4
Thermal Physics 8–12% 6–10
Heat and Temperature 4% 2–4
Kinetic Theory and Ideal Gas Laws 2–3% 1–2
Laws of Thermodynamics 1% 0–2
Heat Engines 2–3% 1–2
Electricity & Magnetism 22–26% 16–20
Electric Fields, Forces, Potential 10% 7–8
Magnetic Fields and Forces 6% 4–5
Electromagnetic Induction 1% 1
Circuits and Circuit Elements 6% 4–5
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Waves 15–19% 11–15
Waves 10% 7–8
Optics 7% 5–6
Modern Physics 8–12% 6–9
Special Relativity 1–2% 1–2
Atomic Models 3% 2–3
Quantum Physics 2% 1–2
Nuclear Physics 3% 2–3
Miscellaneous 2–4% 1–3
Graph Analysis 1–2% 0–2
Equation Manipulation 0.5–1% 0–1
Significant Digits and Lab Skills 0.5–1% 0–1
The chapters of this book are organized according to these categories. If a physics topic is not in
this book, you don’t need to know it. Here’s some other helpful information:
You need to know: the formulas expressing physical relationships (such as F = ma), how to
manipulate equations, how to read a graph
You don’t need to know: trig identities, calculus, three-dimensional vectors and graphs, physical
constants (such as G = 6.67 10–11 N·m2 ⁄ kg2)
Format of SAT II Physics
SAT II Physics is a one-hour-long test composed of 75 questions and divided into two parts. You
can answer questions in any order you like, though you’re less likely to accidentally leave a
question out if you answer them in the order in which they appear. Part A—classification
questions—takes up the first 12 or 13 questions of the test, while Part B—five-choice completion
questions—takes up the remaining 62 or 63 questions.
Part A: Classification Questions
Classification questions are the reverse of normal multiple-choice question: they give you the
answers first and the questions second. You’ll be presented with five possible answer choices, and
then a string of two to four questions to which those answer choices apply. The answer choices are
usually either graphs or the names of five related laws or concepts. Because they allow for several
questions on the same topic, classification questions will ask you to exhibit a fuller understanding
of the topic at hand.
The level of difficulty within any set of questions is generally pretty random: you can’t expect the
first question in a set to be easier than the last. However, each set of classification questions is
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generally a bit harder than the one that came before. You should expect questions 11–13 to be
harder than questions 1–4.
Classification Question Example
Directions: Each set of lettered choices below refers to the numbered questions
immediately following it. Select the one lettered choice that best answers each question
and then blacken the corresponding space on the answer sheet. A choice may be used
once, more than once, or not at all in each set.
Questions 1–3
A boy throws a ball straight up in the air and then catches it again.
1. . Which of the above graphs best represents the ball’s position with respect to time?
2. . Which of the above graphs best represents the ball’s velocity with respect to time?
3. . Which of the above graphs best represents the ball’s acceleration with respect to time?
Explanation
You can usually answer classification questions a bit more quickly than the standard five-choice
completion questions, since you only need to review one set of answer choices to answer a series
of questions.
The answer to question 1 is B. The ball’s position with respect to time can be expressed by the
equation y = –1/ gt2, where g is the downward, acceleration due to gravity. As we can see, the
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graph of y against t is an upside-down parabola. In more intuitive terms, we know that, over time,
a ball thrown in the air will rise, slow down, stop, and then descend.
The answer to question 2 is E. The acceleration due to gravity means that the velocity of the ball
will decrease at a steady rate. On the downward half of the ball’s trajectory, the velocity will be
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