
SAT II Physics TestTaking Strategies
All the strategies discussed above can be applied equally
to SAT II Physics and SAT II Modern Hebrew. That’s why they’re called
“general hints.” However, as you may have noticed, there are a number
of differences between the study of physics and the study of modern
Hebrew. Because physics is unlike modern Hebrew, and even unlike
math and chemistry, there are a number of strategies that apply
uniquely to SAT II Physics. Some of these strategies will help you
out in physics generally, while some are suited to the unique idiosyncrasies
of the SAT II format.
Physics Hint 1: Know Those Formulas!
You aren’t allowed to bring a calculator into the SAT
II, nor are you allowed to bring in a sheet of paper with useful
information on it. That means that if you haven’t memorized formulas
like F = ma and you’re
going to lose a lot of points. As we said earlier, 67–80% of the
test requires that you know your formulas.
This doesn’t mean you have to do a lot of rote memorization.
As you become more familiar with the principles of physics, you’ll
find that the equations that express these principles will become
increasingly intuitive. You’ll find patterns: for instance, the
force exerted at any point in a field, be it a gravitational field
or an electric field, is inversely proportional to r^{2}.
That’s why Coulomb’s Law and Newton’s Law of Gravitation look similar. Knowing
your physics will help you know your formulas.
A lot of people feel burdened coming into an exam with
lots of formulas and equations in their head. It can feel like your
mind is “full,” and there’s no room for the problem solving at hand.
If you have trouble remembering formulas, you might want to look
them over carefully in the minutes before the test, and then, before
you even look at the first question, write down the formulas you
have a hard time remembering on the back of the question booklet.
That way, you can refer back to them without any painful effort
of recollection.
Physics Hint 2: Estimate
This hint goes hand in hand with General Hint 5:
Know What You’re Being Asked. Don’t dive blindly into five
possible answer choices until you know what you’re looking for.
The first way to know what you’re looking for is to understand the
question properly. Once you understand the question, get a rough
sense of what the correct answer should look like.
Estimation is only useful for questions involving calculation:
you can’t “estimate” which Law of Thermodynamics states that the
world tends toward increasing disorder. In questions involving a
calculation, though, it may save you from foolish errors if you
have a sense of the correct order of magnitude. If you’re being
asked to calculate the mass of a charging elephant, you can be pretty
confident that the answer won’t be 2 kg, which would be
far too small, or kg, which would be far
too big. Estimation is a good way to eliminate some wrong answers
when you’re making an educated guess.
Physics Hint 3: Put It on Paper
Don’t be afraid to write and draw compulsively. The first
thing you should do once you’ve made sure you understand the question
is to draw a diagram of what you’re dealing with. Draw in force
vectors, velocity vectors, field lines, ray tracing, or whatever
else may be appropriate. Not only will a visual representation relieve
some of the pressure on your beleaguered mind, it may also help
the solution jump right off the page at you.
Drawing graphs can also make a solution appear out of
thin air. Even if a problem doesn’t ask you to express anything
in graphic terms, you might find that a rough sketch of, say, the
velocity of a particle with respect to time will give you a much
clearer sense of what you’re dealing with.
And don’t forget to write down those equations!
Writing down all the equations you can think of may lead you to
a correct answer even if you don’t really understand the question. Suppose
you know the problem deals with an electric circuit, and you’re
given values for current and electric potential. Write down equations
like V = IR and P = IV, plug
in values, fiddle around a little, and see if you can come up with
an answer that looks right.
Physics Hint 4: Answers Are Not Convoluted
Remember, on SAT II Physics you’re not allowed to use
a calculator, and you’re only given, on average, 48 seconds
to answer each question. If you’re working on a problem and find
yourself writing out lines and lines of simultaneous equations,
trying to figure out or trying to recall your
trig identities, you’re probably on the wrong track. These questions
are designed in such a way that, if you understand what you’re being
asked, you will need at most a couple of simple calculations to
get the right answer.
Physics Hint 5: Eliminate Wrong Answers
In General Hint 6: Know How To Guess, we
explained the virtues of eliminating answers you know to be wrong
and taking a guess. On most questions, there will be at least one
or two answer choices you can eliminate. There are also certain
styles of questions that lend themselves to particular processofelimination
methods.
Classification Questions
Questions 1–3 relate to the following quantities:

The weakness of classification questions is that the same
five answer choices apply to several questions. Invariably, some
of these answer choices will be tempting for some questions but
not for others. For instance, you can be pretty sure that kinetic
energy isn’t measured in hertz: E may be a tempting
answer choice for other questions but not for that one, so you can
eliminate it.
Another point that may help you guess in a pinch is that
you’ll rarely find that the same answer choice is correct for two
different questions. The directions for classification questions
explicitly state that an answer choice “may be used once, more than
once, or not at all,” but on the whole, the ETS people shy away
from the “more than once” possibility. This is by no means a sure
bet, but if you’re trying to eliminate answers, you might want to eliminate
those choices that you’ve already used on other questions in the
same set.
If you’re wondering, the answers to the above questions
are 1 A, 2 E, and 3 D.
“EXCEPT” Questions

Questions of the “EXCEPT” variety contain a bunch of right
answers and one wrong answer, and it’s generally possible to spot
one or two right answers. Even if you can’t answer the question
confidently, you might remember that alpha particles have a positive charge
and that they are identical to the nucleus of a helium atom. Already,
you’ve eliminated two possible answers, and can make a pretty good
guess from there.
If you’re interested, the answer is D: Rutherford’s
gold foil experiment showed that alpha particles would occasionally
deflect off the gold foil at extreme angles, thus proving that atoms
have nuclei.
“I, II, and III” Questions

In this style of multiplechoice question, the “I, II,
and III” questions provide you with three possible answers, and
the five answer choices list different combinations of those three.
There’s an upside and a downside to questions like these. Suppose
you know that a concave mirror has f > 0 and
a convex mirror doesn’t, but you’re not sure about a converging
lens. The downside is that you can’t get the right answer for sure.
The upside is that you can eliminate B, D,
and E, and have a 50% chance of guessing the right
answer. As long as you’re not afraid to guess—and you should never
be afraid to guess if you’ve eliminated an answer—these questions
shouldn’t be daunting.
The value of f for a converging
lens is positive, so the answer is C.
Physics Hint 6: Be Flexible
Knowing your physics formulas is a must, but they’re useless
if you don’t know how to apply them. You will probably never be
asked to calculate the force acting on an object given its mass
and acceleration. Far more likely, you will be asked for the acceleration
given its mass and the force acting on it. Knowing that F
= ma is useless unless you can also sort out that a
= F⁄m.
The ETS people don’t want to test your ability to memorize
formulas; they want to test your understanding of formulas and your
ability to use formulas. To this end, they will word questions in
unfamiliar ways and expect you to manipulate familiar equations
in order to get the right answer. Let’s look at an example.

What’s the universal gravitational constant? Some people
will know that this is the G in the equation
for Newton’s Law of Gravitation: . Other people won’t know
that G is called the “universal gravitational
constant,” and ETS will have successfully separated the wheat from
the chaff. It’s not good enough to know some formulas: you have to
know what they mean as well.
Given that we know what the universal gravitational
constant is, how do we solve this problem? Well, we know the satellite
is moving in a circular orbit, and we know that the force holding
it in this circular orbit is the force of gravity. If we not only
know our formulas, but also understand them, we
will know that the gravitational force must be equal to the formula
for centripetal force, . If we know to equate
these two formulas, it’s a simple matter of plugging in numbers
and solving for r.
Knowing formulas, however, is a small part of
getting the right answer. More important, you need to know how to
put these two equations together and solve for r.
On their own, without understanding how to use them, the equations
are useless.
But there are two slightly underhanded ways of getting
close to an answer without knowing any physics equations. These
aren’t foolproof methods, but they might help in a pinch.
Slightly Underhanded Way #1: Elimination through
Logic
By scanning the possible answer choices, you can see that
the answer will begin either with a 4 or a 2.5. There are three
options beginning with 4 and only two beginning with 2.5. Odds are,
the correct answer begins with 4. The test makers want to give you
answer choices that are close to the correct answer so that, even
if you’re on the right track, you might still get caught in a miscalculation.
Second, make a rough estimate. At what sorts of distances
might a satellite orbit? We can eliminate A immediately:
that answer has our satellite orbiting at 4 cm from the center of
the Earth! That leaves us with a choice between B and C.
Those aren’t bad odds for guessing.
Slightly Underhanded Way #2: Work with the Letters
This is a method for those of you who like manipulating
equations. From looking at the answer choices, you know the answer
will be in meters. You’ve been given three quantities, one expressed
in m/s, one expressed in kg, and one expressed in N·m^{2}/kg^{2}.
These are the only three quantities you’ll be asked to draw upon
in order to get your answer. Because F = ma,
you know you can substitute kg·m/s^{2} for
N. So a quantity expressed in N·m^{2}/kg^{2} can equally
be expressed in m^{3}/kg·s^{2}.
The trick, then, is to combine a quantity expressed in
these terms with a quantity expressed in meters per second and a
quantity expressed in kilograms, and wind up with a quantity expressed
solely in meters. To do that, you need to get rid of the “kg” and
the “s” by canceling them out. Start by canceling out the “kg”:
Now you need to cancel out the “s^{2}”
in the denominator. Let’s divide by the square of our “m/s” quantity:
There you have it. You didn’t need to use a single formula
to get the answer. You just had to be aware of the terms in which
your answer needed to be expressed, and manipulate the quantities
you were given in the question.
Word to the wise: don’t use this method unless you’re
absolutely stumped. It can backfire, and is of course no substitute
for careful reasoning.
