# Tips for the SAT Physics Subject Test

Biology SAT? Check. Chemistry SAT? Check. Physics SAT?

Physics SAT?

There’s a reason why I saved this SAT subject for last in my SAT science series: I don’t like it. I know it’s weird, since I like science and I love math, but physics never appealed to me. Thankfully though, the physics test is the most straight forward of the three science SATs. Just like the other science SATs, the first 10-15 questions are classification sets, where the test gives you a word bank of five answer choices and you match each question with one of the five choices. The remainder of the test’s 75 questions are traditional 5-answer multiple choice questions.

The College Board gives you a handful of practice questions, but beyond reviewing your physics notes, what else can you do? Well, you can start with…

## Tip 1: Get good at spatial thinking.

How good are you at drawing free body diagrams from scratch? Surprise, the Physics SAT doesn’t care! A lot of the questions will be accompanied by a diagram that the test takers made just for you. Like so:

(A) -4 kg·m/s
(B) -1 kg·m/s
(C) 0 kg·m/s
(D) 1 kg·m/s
(E) 4 kg·m/s

There are mechanics questions that ask you about acceleration and displacement. There are optics question that ask you about lenses and the images they create. There are electricity and magnetism question about charges, currents, and forces. But the common thread to all these physics topics is understanding how their diagrammed. Look for the initial conditions they give you and translate the question so you know exactly what you’re looking to answer.

## Tip 2: Understand linear, inverse, and quadratic relationships.

Almost everything on the physics test can be described by a formula. And there are about 695841859649* different formulas and variations out there. But luckily, you don’t need to memorize them all. But what you should understand are how two variables are linked with one another. Take this question.

(A) P/4
(B) P/2
(C) P
(D) 2P
(E) 4P

A lot of the questions on the test ask you to double this, triple that, and halve that other thing. Instead of going into your memory bank and trying to fish out the exact formula that ties voltage (the thing you’re changing) and resistance (the thing that’s constant) to power (the thing you’re measuring), it’s easier for me to think about how they relate to one another.

For one thing, I know Ohm’s Law, which says that voltage has a linear relationship with current and resistance. That means that if I double the voltage but keep resistance the same, I’ll double the current. Likewise, I know the power law (or whatever it’s called, I’m not actually sure) which says that power has a linear relationship with voltage and current. If I halve the voltage but keep current the same, I’ll halve the power.

You have two linear relationships that link these variables together, so what happens if you double voltage but keep resistance constant? Notice how you are multiplying one linear relationship by another, and that will get you to the correct answer.

Finally, don’t forget that quadratic relationships can also be inverse. Think about the formula for gravitational force or electrical force. If you double the distance between two objects while keeping their masses/charges the same, you reduce the force by a factor of 4. Likewise, if you halve the distance between them, you quadruple the force.

## Tip 3: Brush up on your chemistry.

The majority of physics classes usually shake out like this. You study the laws of motion and energy in the first half and then the laws of electricity and magnetism in the second half. You sprinkle in some of the leftover topics, like sound waves and optics, somewhere in between.

However, there are a few topics that your physics class may not cover, possibly because you might have covered them in chemistry. I’m talking about things like heat transfer, radioactive decay, and subatomic particles. The SAT puts these topics on both the Physics and Chemistry SAT, so make sure to review these as well.

Hang in there. You’ll make it through.

Tip 1: A, -4 kg·m/s
Tip 2: E, 4P

## Author

• Jon has a degree in neuroscience from Johns Hopkins University and a degree in science journalism from New York University. It's safe to say that he's learned a lot of things over the past decade, but he's learned how to write about those things too. All the while, he’s been tutoring students, helping them better understand their own coursework and showing them how to crack the code of the SAT and ACT. When he's not doing that, you can usually find him singing, playing violin, or coming up with bad puns.

### 2 Responses to Tips for the SAT Physics Subject Test

1. hcs April 23, 2018 at 12:54 pm #

in the answers to examples, first question, how
can the *magnitude* of the change in the east-ward
component of the momentum be *negative*? isn’t the
magnitude of a quantity always positive and so the answer
change in momentum in the easterly direction, then,
of course, the answer would be -4m/s (final momentum minus
the initial momentum = 0 – 4 = -4 m/s)

• David Recine April 26, 2018 at 9:49 am #

You’re correct that magnitude cannot be negative. To clarify, though, there is one instance when magnitude isn’t positive: magnitude can also, of course, be 0, which is neither negative nor positive. But change in magnitude can be negative, because change measures whether the magnitude becomes greater (positive change) or smaller (negative change). And since the passage is asking for the change in magnitude rather than the magnitude of change, the negative sign only indicates a change downward, and not a truly negative measure of magnitude.

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