Prepping for the SAT Subject TestTM in Physics

Update: We are suggesting that the majority of students who wish to take the Physics SAT do so on August 24 as opposed to June 1. There is just too much material that most physics classes omit, and spending some of your summer reading up on (especially) magnetism and waves will really bolster your score. Unless your class has already covered this material, or you have learned it independently, the August 26 administration will likely be your best option.

In the NYC area, we are able to work in person as well as virtually for this test. Please inquire and we can discuss.

To begin, take a diagnostic test!  You will start by taking the first SAT Physics practice test published by the College Board (these are not hard to get ahold of). Allot yourself exactly one hour, with a timer. It is very important you not go over the allotted time, (unless you get time and a half) so that you can assess where you are and how best to design a study plan going forward. Please note this is a real test, and as such serves as an excellent benchmark. Also: Do NOT take this until you are about 8 weeks away from the end of your physics course, because you will still need to cover a fair amount of material.

Essential Facts You Need To Know Before Getting Started: 

•LENGTH: The test consists of 2 sections of 75 questions total for which you have 60 minutes.
•QUESTION FORMAT: A – E multiple choice; Part A is “matching sets” which we will describe below and Part B is straight multiple choice.
•MATERIAL COVERED: The recommended prior coursework is a year of physics that includes vectors, and for which algebra and trigonometry is the general prerequisite.
•TOPICS INCLUDED: See ”Topics Covered” in the preamble of  the College Board SAT Physics test. This gives a breakdown of topics by percent, and you should definitely read it carefully, and circle ALL areas where you feel you are weak. In fact, your FIRST task should be to review these subjects and circle the ones you are weakest in. This is of course important for the preparation strategy, because if you are weak on Newton’s Laws and kinematics that is a much larger percentage of the test than Modern Physics.
•Calculators are NOT allowed.

General Strategies: We are going to examine some general test strategies and then focus in on some question specific strategies, with specific examples.

General Strategy 1: Think Process of Elimination (POE) Think about each question you see in terms of process of elimination. Do not try to determine what the answer is; rather, ask yourself what the answer is not. Why is this? Because for a large percentage of the test, you will have to take your best guess at the correct answer. Since the answer is in front of you, there is a statistical likelihood that you will guess correctly by eliminating at least one of the answers.

For example, suppose you have 10 questions, each with answers A-E. The College Board gives you plus one point for each correct answer, minus one quarter point for each incorrect answer, and no points for any answers left blank. Let’s say you eliminate one answer that you know is wrong from all ten questions. For the sake of argument say this is “E”. Now, you guess randomly from the remaining answer choices, A through D. Statistically you will guess correctly one time out of four. How many points will this get you?

2.5 Correct = 2.5 points x +1 point =   +2.5 points

7.5 Wrong = 7.5 points x -1/4 points = -1.9 points

You Score                                                             +0.6 points

This is enough to raise your score from a 690 to a 700.

Therefore, Always guess if you can eliminate one answer. NEVER GUESS if you CANNOT ELIMINATE AT LEAST one answer.

Nature of the Physics SAT Subject test The SAT Physics Subject Test is 75 Questions in total, divided into 2 parts, A and B. It is 1 hour long, and calculators are not allowed, so take your practice tests without calculators.

Part A  A total of 11-15 questions, presented as matching sets. Approximately questions #1- #15

Part B  A total of 60-65 questions, straight multiple choice. Approximately questions #16-#75

General Strategy 2: Know how the order of questions pertains to the difficulty of the question. Let’s review how the Physics SAT is structured in terms of question difficulty:

In Part A, there is a general increase in the order of difficulty with each question group. That is, if questions 7-9 are one group, the questions get more difficult as you go through them, and then start off as easy again when you get to question 10-13.

In Part B, the beginning questions are easy and they get increasingly more difficult. One can assume the first third are “easy”, the second third “medium”, and the last third are “difficult”.

That is,

Approximate question number                        Difficulty level

16 – 33                                                                          Easy

34 – 50                                                                          Medium

51 – 75                                                                          Difficult

What do we really mean though, by “difficult”? It is important to define the concept of “difficult”, as far as the SAT tests are concerned. A difficult question is not necessarily a question that asks you something conceptually difficult. Rather, a “difficult” question is a question that most people get wrong. That is, for a difficult question, the answer that looks like the correct answer almost never is the correct answer, but because most people pick that as the answer choice, it is answered incorrectly much more frequently. So on the difficult parts of the test, if you find yourself answering the question with the answer choice that “looks” correct, it in fact is almost never correct. Put differently, the more difficult the question, the more likely there’ll be several traps. Paying attention to the order of difficulty will help you determine when to go with your gut and when to eliminate answers that feel “too easy.”

Why is it necessary to discuss this? First, it is always to your advantage to tackle the easier problems on a test before going to the tougher ones, and this goes for your non- standardized tests as well. But more importantly, these tests are curved, and the curve is somewhat predictable. That is, you need not answer all the questions to get a high score. Further, you score the same number of points for each correct answer regardless if that question is easy or difficult. Question 1 gets +1 point, as does question 72. Likewise, an incorrect answer receives –1/4 point, no matter the location of the error. Thus, it makes sense to omit certain questions if you absolutely can’t answer them (ie cannot eliminate one answer choice), if you don’t need to answer all of them to get a high score. Since you receive the same +1 points for each correct answer regardless of where you answer the questions, the questions you choose to omit should come from the more difficult sections, ie, the sections at the end. What you should be reading into this, then, is that you need not answer all of the questions in order to get a high score.

So, what is the curve? For the physics test, it is fairly reproducible that you will score at least 700 if you receive a “raw score” of 45-47. This means you can answer 45-47 questions correctly, without making any mistakes, and get a 700…in other words, you can omit more than a whole third of the test. Which third should you omit? The more difficult third! Of course, you are probably not going to get every one of those questions in the first 45-47 correctly, but the point is that when you are going to omit answers – and we are saying you can – you should try and save the blanks for the most difficult portions of each section.

For you physics studs and studettes, your 800 scores can be had for the price of 16 or so additional correct answers, from either section 1 or 2. Note that this means you can get an 800 if you answer 63 questions correctly, while ignoring the remaining twelve.

Now, however lets go back to our original statement: ALWAYS GUESS IF YOU CAN ELIMINATE ONE ANSWER. Always guess if you can eliminate one answer. NEVER GUESS if you CANNOT ELIMINATE AT LEAST one answer. Even considering the curves, the statistics are in your favor if you guess when you can eliminate one answer. Your score WILL go up.

Some Question Strategies, Part A

Part A has about 3 matching sets, with 3-7 questions each. Think Process of Elimination!

For example, questions 1-4 might read

A) Newton’s First Law

B) Newton’s Third Law

C) Radial Acceleration

D) Impulse

E) Conservation of Energy

1. Velocity of a falling object from a given height
2. Change in momentum with time
3. Mathematical expression uses square of velocity
4. Reason a rocket works in outer space

Note: The same answer may appear more than once, or not at all.

Now, because we all have a tendency to work less accurately and less precisely when we are under pressure, and we are thinking in terms of process of elimination, we might have crossed out 4 letters by the time we get to problem 2. How will we remember which ones we have crossed out, and which we haven’t? To keep track of what we have crossed out and what we have not crossed out, it helps to create a grid to the right of the answer choices, as such:

                                                                                                                              A   B   C   D   E
1. Velocity of a falling object from a given height
2. Change in momentum with time
3. Mathematical expression uses square of velocity
4. Reason a rocket works in outer space

So your test page will look like:

                                                                                                                             A   B   C   D   E
1. Velocity of a falling object from a given height                      x    x    x    x
2. Change in momentum with time                                                   x    x    x          x
3. Mathematical expression uses square of velocity               x    x          x    x
4. Reason a rocket works in outer space                                       x          x    x    x

Note this seems to work for about 75% of the students who try it. We won’t insist, but you might want to see if it does indeed work for you!

Some Question Strategies, Part B

Part B is straight multiple choice. Again work by trying to eliminate answers, and thinking about the question’s level of difficulty based upon its number. And again, this bears repeating: if you can eliminate one answer choice, guess from the remaining four.

Some question types you will see (some prep books have 4 statements, probably inaccurate):

I/II/III questions:

I – You know nada

II -You know this is wrong. Cross out C, D, and E.

III – You know nada

A) I and III are correct
B) Only I is correct
C) Only II is correct
D) I, II, and III are correct
E) II and III are correct

Now, guess between A and B. Your chances of getting this answer correct are now 50%, where they were originally 20%.

For example:

A girl skis down a slope which has a coefficient of
kinetic friction of 0.1. Which of the following statements
are true about her acceleration?

I) The normal force exerted on the girl affects her acceleration. You don’t know if this is true or not

II) Her acceleration must be the same as gravity. You know this is wrong, cross out C, D, and E

III) Her rate of acceleration remains constant as she goes down the hill. You don’t know if this is true or not

A) I and III are correct
B) Only I is correct
C) Only II is correct WRONG
D) I, II, and III are correct WRONG
E) II and III are correct WRONG

Note this is just one possible combination of answer choices.

EXCEPT/LEAST/NOT type questions. These are always in LARGE TYPE. Put your thumb over the “EXCEPT”, the “LEAST”, or the “NOT”, and cross out all that are affirmative, then guess form remaining answers.

For example:

A proton enters a uniform magnetic field at constant
velocity, perpendicular to the proton’s motion. Upon
entering the field, all of the following will happen EXCEPT:

A) The proton will begin traveling in a circular motion
B) The proton will experience a change in speed
C) The proton will experience a change in velocity
D) The proton will experience a force inversely proportional to its velocity
E) The direction of the magnetic field will influence the motion of the proton

Thinking in terms of what WILL happen to the proton tends to make this easier than to think about what WILL NOT happen.

Question Strategies you will have heard of, which are maybe not so useful for the Physics SAT:

A strategy you will use for the Math Level 1 and Math Level 2 SAT tests is “backsolving”, which is useful all of the answer choices are numerical, and the question asks you for the value of a single variable. This technique is not useful if the question does not ask to solve for a variable, or it asks to solve for more than one variable.

It is very rare to see a problem like this on the SAT Physics Subject test, and you are most likely not going to use it. But we will review it here briefly under the “just in case” scenario.

If you encounter a problem that asks you to solve for a single variable, AND all of the answers are numerical: Look at the answers, take the intermediate value, and plug this into the equation. Do not try and solve the equation, as the answer is in front of you. See if the intermediate value solves for the variable, and if it doesn’t, work from there. Do not feel that you absolutely MUST use this strategy, as solving the problem mathematically will sometimes prove the faster option. But backsolving is useful when you are asked to “solve for x”, and you see answer choices with numerical values.

A second strategy that is useful for the Math Level 1 and Math Level 2 SAT, which we will mention here in passing: Inserting an integer or a number, when the answer choices are variables, rather than solving for the variable in question. Again, since this is unlikely to appear on your Physics SAT Subject test, but is mentioned so often as a staple of standardized test prep, we thought we should mention it here as well.

Remember, no amount of test taking tricks or techniques will help you if you don’t understand vectors and Newton’s Laws. There is no such thing as getting a high score on a test if you don’t know the subject material. Test taking techniques are useful, and much of what you would need to know is encapsulated here, but if your course grade is a B -? Forget the Physics Subject Test and concentrate on bringing your course grade up! By the way, since many of the problems with physics materialize in the first half of the year and then continue, here is a good place to start:

Physics concepts from the beginning of the year that you simply MUST know!

Two other blogs you may find useful are

I am taking AP Physics and doing well. Should I take the SAT Physics Subject test?

And

So many Physics courses! Which one prepares you for the SAT Physics Subject Test™?

Good luck! Be sure to give us a shout if you have any questions.

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