Which AP Physics Course Should I Take?

Considering an AP Physics course? Outstanding, but which course should you take? The College Board now offers four separate and distinct versions of AP Physics, each designed with very different content, styles, and levels of mathematical complexity.

Currently, the four physics courses offered are AP Physics 1, AP Physics 2, AP Physics C: Mechanics, and AP Physics C: Electricity and Magnetism. So let’s start by talking about the courses and what each has to offer.

Algebra-Based Courses

The new AP Physics 1 and 2 courses are both algebra-based courses, meaning no knowledge of calculus is required, though students should be comfortable with basic algebra and trigonometry. The exams for these courses were first offered in May of 2015, so the courses and the exams are still evolving through their infancy. Further, the AP Physics 1 and AP Physics 2 courses include a strong emphasis on conceptual understanding and critical thinking. Compared to traditional physics courses, these courses include a significant amount of reading and structured writing, experimental design, and critical thinking.

Though mathematical reasoning and problem-solving are required for success in the course, they aren’t emphasized as strongly as in traditional courses. The courses are centered around seven “big ideas in physics,” and many of the exam problems will test your ability to interpret and apply one or more of these ideas to a new and unique situation (sometimes referred to as a transfer task).

Like most introductory physics courses, both AP Physics 1 and AP Physics 2 include a strong lab component to help students develop proficiency in science practices which are crucial to success. The course as a whole focuses on the idea that physics is something you do, not just something you know.

The associated AP exams for these courses consist of two sections: a 90-minute multiple choice section and a 90-minute free response section. The multiple choice section consists of 50 to 55 questions with four answer choices per question. Unlike most multiple choice tests, however, certain questions may have multiple correct answers that need to be chosen to receive full credit.

The free response section consists of four or five questions. Typically one question will cover experimental design, one question will cover quantitative and qualitative problem solving and reasoning, and three questions are of the short answer variety. In addition, students are expected to articulate their answers with a paragraph-length response.

AP Physics 1

The AP Physics 1 course itself is designed as a first-year physics course. The bulk of the course centers around traditional Newtonian Mechanics, beginning with the study of motion (kinematics), forces (dynamics), work, energy, power, linear momentum, circular motion and rotation, gravity, and oscillations. In addition, AP Physics 1 also includes a brief introduction to mechanical waves, basic electrostatics, and simple electrical circuits.

AP Physics 2

AP Physics 2 is designed as a follow-up to AP Physics 1, utilizing the same course philosophy, but extending the content covered to include fluids, thermal physics, a deeper look at electrostatics and more complex electrical circuits, magnetism, optics, and modern physics.

Calculus-Based Courses

The two AP Physics C courses both incorporate calculus, so students should have calculus as a pre-requisite or co-requisite for the best possible experience. AP Physics C: Mechanics can be offered as a first-year physics course, though some schools offer both AP Physics C: Mechanics and AP Physics C: Electricity and Magnetism in the same year to students who have prior physics courses in their background.

Compared to AP Physics 1 and AP Physics 2, the AP Physics C courses follow a more traditional path with a stronger emphasis on quantitative problem solving. The level of calculus complexity is relatively light, with a strong focus on application of principles to various situations as opposed to the longer written explanations of the AP–1 and AP–2 courses.

AP Physics C: Mechanics

Similar to AP Physics 1, AP Physics C: Mechanics covers only traditional Newtonian Mechanics. Students study motion, forces, work, energy, power, linear momentum, angular momentum, circular motion, rotational motion, gravity, and oscillations. Compared to AP Physics 1, however, the C course incorporates a higher level of technical complexity, such as dealing with situations of a non-constant acceleration, incorporation of drag forces (such as air resistance), and calculations of rotational inertia.

Both of the AP-C exams consist of roughly 35 multiple choice questions given in a 45-minute interval, followed by three free response questions in a second 45-minute interval. The AP-C exams are typically given back to back on the same afternoon.

AP Physics C: Electricity & Magnetism

The AP Physics C: Electricity & Magnetism course is by far the most technically complex of the AP Physics courses. Beginning with electrostatics, the course includes a detailed look at charges, electric forces, electric fields, electric potential, and capacitors. These concepts are then applied to an analysis of electrical circuits, including circuits with multiple sources of potential difference, real and ideal batteries, and transient analyses of circuits which include capacitors.

From there, the course transitions into a look at magnetism, with a strong focus on the relationships between electricity and magnetism as Maxwell’s Equations are investigated. It’s typically in this section that students really begin to challenge themselves, applying fundamental relationships (and calculus skills) to problems of increasing sophistication and technical complexity. With the added knowledge of magnetism, inductors are also discussed and tied back into the analysis of electrical circuits.

As you can see from the course descriptions, both of the AP Physics C courses are quite limited in scope, allowing for a much deeper exploration of the fundamental relationships and their application to various problems and situations.

Long-Term Goals

So then, back to our original question – which AP Physics course should you take? The answer, as is so often the case in life, is that it depends. Students who are planning on a career in engineering or physics should definitely consider the calculus-based courses (AP Physics C). These courses are fundamental to future studies, and a majority of colleges and universities accept scores of 4 or 5 in these courses for credit (though many students choose to re-take these courses to further cement their understanding of the fundamental concepts and boost their freshman GPA).

AP 1 2 C Table 001

For students who aren’t planning on a career in engineering or physics, the AP Physics 1 / AP Physics 2 series might be a better answer if their school of choice accepts AP–1/2 credit, as AP Physics C could be “overkill” compared to future course requirements. The problem, however, is that the AP Physics 1 and AP Physics 2 courses are so new that many colleges don’t know how to deal with them, and as of the writing of this article, there aren’t many schools that provide college credit for strong scores on the exams, as the course content and philosophy often times don’t match up well with the college’s offerings. For this reason, students who are up for a challenge and enjoy problem solving may want to target the AP Physics C course, even if they aren’t planning on a career in engineering or physics. Many universities will give credit for a good score in AP Physics C as a general science credit.

To complicate matters, there are often times opportunities to take a sequence of these courses. In many high schools, AP Physics C is offered as a second-year physics course, with students taking on both the Mechanics and E&M courses in a single year. It’s a fast-paced course, but doable for those who have successfully passed an introductory physics course. For those taking physics for the first time, AP Physics C: Mechanics is a reasonable year-long endeavor. Some schools with extended class times offer both AP–1 and AP–2 in the same year, though this is a very aggressive undertaking.

Summarizing the Choices

To summarize as best I can in this nebulous time period, AP Physics C courses are traditionally for students heading toward physics and/or engineering related career paths, and require a pre-requisite or co-requisite in calculus. Definitely take AP-C Mechanics before AP-C E&M, though it is possible to do both in the same year, especially with some prior physics background. For students not taking calculus or not headed toward physics or engineering careers, AP Physics 1 is a great place to start, with AP Physics 2 a reasonable follow-up for those interested. The concern with these choices is the newness of the courses, and whether colleges and universities will give credit for a strong AP score. As always, discussing and planning out course selections with a guidance counselor in consultation with an admissions counselor is highly advised.

Strategies for Success

Regardless of which course(s) you choose, the AP Physics courses are challenging courses that require a level of independence and personal accountability to learn the material. These courses aren’t designed for “spoon feeding,” in which the instructor lectures, students listen, and everything works out. In order to truly understand the material and perform well on the culminating exam, you must engage in the class on a daily basis, struggle through the challenging problems, make mistakes again and again, and learn from them. Actively participate in classroom and lab activities and discussions, ask questions, but be prepared to search out your own answers. And don’t be afraid to take a step back every now and then and think about how what you’re learning applies to the course goals as a whole. Concept-mapping or outlining the topics in the course can be a terrific way to make connections you might not otherwise recognize.

And of course, you have tons of resources to help you. Beyond just your textbook (which I do recommend you actually open and actively read) and teacher, you’ll find outstanding video tutorials and Q&A forums like those at Educator.com, discussion and homework help communities, “cheat sheets,” and extra problems at APlusPhysics.com, and of course there are some great review and companion books available for these specific courses.

 

About the Author 

Dan Fullerton is the author of AP Physics 1 Essentials, AP Physics 2 Essentials, and the APlusPhysics.com website.  He is an AP Physics teacher at Irondequoit High School in Rochester, NY, and was named a New York State Master Physics Teacher in 2014.

 

AP and Advanced Placement Program are registered trademarks of the College Board, which does not sponsor or endorse this work.

What I Learned at Educator.com Filming AP Physics C in Two Weeks

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It’s my last day on the west coast following two weeks of recording at the Educator.com studios in Los Angeles.  I’ve completed filming of the AP Physics C: Mechanics and the AP Physics C: Electricity and Magnetism courses, and roughly 18 months ago finished recording the AP Physics 1 and AP Physics 2 course sequences.  At the conclusion of this massive effort, I thought it fitting to take a few minutes and summarize what I’ve learned from the experience.

First, I’m amazed at the total amount of content involved in these projects when all was said and done.  The AP Physics 1/2 course includes more than 930 slides, and the AP Physics C total is up over 950.  Coupled with diagrams, formulas, and illustrations, these represent roughly a year’s worth of full-time effort, squeezed in to an already busy schedule with early morning work, weekends, and middle-of-the-night can’t sleep sessions.

Second, I’ve recognized how challenging the content truly is for the AP-C course.  I had some of the content prepared already from my APlusPhysics videos, yet it still took me more than 5 months to create the more-detailed Educator.com lessons.  I designed each lesson in detail, and even made notes on what I would discuss, derive, and explain on each individual slide.  When I reached the studios in LA, however, I still had tons of preparation work to do.  Each day I rehearsed every lesson three times before filming.  I’d go over the lessons in detail (including solving all problems and writing out all derivations in my notebook) over an extended dinner each night in the hotel, then go back to my hotel room and do it all again while listening to a baseball game before bed.  Early the following morning, I’d get up around 5 am and go through it once more before our 9- or 10-am filming session would begin.  Once filming for the day was complete, I’d do it all again in preparation for the next set of lessons.  I wonder if I didn’t do more physics homework in my two weeks of filming in LA than my students do in an entire year.

I found as I went through this that every time I solved a free response problem or walked through a derivation, I found slightly different methods of solving the problem.  Some were smoother than others; some were longer than others.  Even though my final passes were usually “cleaner” than my initial solutions, I tried to stick with my initial solutions in the videos to better mirror the approach students might take.

Even with all that preparation, the recording sessions were still quite stressful.  In walking through the lessons, there were technical components to the presentation that were fairly unforgiving.  Hit the wrong button in the wrong order and you’d have to start all over again.  Switch colors and then switch slides before writing and you’d have to do it all over again. Cough, sneeze, or forget where you are in a lecture or stump yourself — you got it, do it all again.  Thankfully, I’d had quite a bit of experience in this sort of thing from my previous trip out to LA to record the AP-1/2 series, so the amount of “re-do” work was kept to a minimum due to all that preparation.  But recording four hours of video lessons sure felt like a 12+ hour day.

In addition, I still found the AP-C material challenging.  In my classroom, I prepare with 42-minute lessons, and the longest I ever lecture in a row is one entire 42-minute period (and I try to avoid that like the plague).  Here, the lessons are straight lecture, with no breaks, no edits, no room for error.  That leaves a lot of material to have down cold while also dealing with technical concerns.  My detailed noted were invaluable, and I referred to them throughout my lectures to make sure I covered all the salient points in each slide, as well as having calculations pre-solved, as opposed to making viewers wait while I punched numbed into my calculator.  With my preparation, my time between lessons was approximately 10 minutes or so to get a quick drink, review the slides for the next lesson for any last-minute issues, and allow the technical folks to prepare the studio for the next round.  Others in the studio, however, would take extended time between recording lessons in order to prepare.  They had the luxury as they were fairly local to the studios, and could spread their recording work out over months.

Working through these courses from start to finish in such a detailed manner in such a compressed time span provides a unique perspective on the course.  Each lesson is designed to present a concept as simply as possible, illustrate that concept, and then demonstrate its application in a variety of scenarios.  In creating these courses I solved every released AP-C free response problem going back to 1998, as well as a scattering of earlier problems.  With the entire breadth of the course fresh in my mind, I’m confident the foundational principles emphasized in the course provide excellent preparation for students taking the AP Physics C exams.  

One of my goals in creating these courses was to provide a more streamlined video series than their previous video series.  Their previous courses totaled 48 hours for mechanics, and 41 hours for electricity and magnetism.  My goal was to cut each of those at least in half, allowing students to minimize their time watching videos, and instead maximize their time actively working with the material.  I haven’t seen the final count for the new courses, but I’m confident we’ll be close, if not under, our target.

Uncle bob has a toupee hg clr st

I’m also excited that the College Board will be allowing students the use of formula sheets and calculators throughout the entire exam next year.  Even after studying and preparing all day every day for weeks, I still referenced my formula sheets and notes in solving problems and preparing.  Memorizing formulas does not constitute learning or understanding, and removing the requirement to have all these formulas memorized will allow students to better focus on what is important.

Finally, I knew being gone from my family for two weeks would be difficult.  I have a two-year-old and a four-year-old daughter at home, and they are already growing up way too fast.  I treasure my time with them, especially our time in the summer when Daddy-Daughter Day Care includes swimming, playing around out back in the sandbox and water table, riding bikes, playground time, and so on.  But it’s been even tougher than I expected.  I’m so thankful for modern technology which allows me to see them and talk to them each day, but when your little girls says all she wants is you to curl up in bed with her after story time at night, it tugs on your heart strings something fierce.

I’m proud of what we’ve put together here at Educator.com through these efforts, and hopeful that students across the world will find these videos helpful in their studies.  I’m also excited to know that I will be able to use these resources with my students in the coming years.  I’m relieved to have finished this project, eager to refocus my efforts on other projects such as revisions to AP Physics 1 Essentials and completing AP Physics 2 Essentials, but most importantly, I can’t wait to get home and hug my girls.

Unrolling Toilet Paper

In his Dec. 17 Action-Reaction blog post titled “Falling Rolls,” one of my heroes of physics instruction, Frank Noschese, details an exercise from Robert Ehrlich’s book Why Toast Lands Jelly-Side Down.

The exercise, a rotational motion problem that challenges students to find the ratio of heights at which you can drop two identical toilet paper rolls, one dropped regularly, the other dropped by holding onto the end of the paper and letting it unroll, such that the two rolls hit the ground at the same time.  It’s a terrific, easy-to-replicate and demonstrate problem that pulls together a great number of rotational motion skills –> finding the moment of inertia, applying the parallel-axis theorem, identifying forces and torques from free body diagrams, and converting angular acceleration to linear acceleration. My students dove into the challenge with zest!

To begin the exercise, we set our variables (H=height for dropped roll, h=height for unrolled roll, r = inner diameter, R = outer diameter), then identified the time it takes for the dropped roll to hit the ground using standard kinematics:

 {t_{drop}} = \sqrt {{{2H} \over g}}

Next, we did the same thing for the unrolling toilet paper roll:

 {t_{unroll}} = \sqrt {{{2h} \over a}}

Of course, if we want them to hit at the same time, the times must be equal, therefore we can show:

 {H \over h} = {g \over a}

Obviously, what we really need to focus our efforts on is finding the linear acceleration of the unrolling roll. To save ourselves some time, we started by looking up the moment of inertia for a cylinder:

 I = {\textstyle{1 \over 2}}M({r^2} + {R^2})

Using the parallel-axis theorem to account for the unrolled roll rotating about its outer radius we find:

 I = {\textstyle{1 \over 2}}M({r^2} + {R^2}) + M{R^2} = {\textstyle{1 \over 2}}M({r^2} + 3{R^2})

Next, we can use a free body diagram to identify the net torque on the roll as MgR, and use Newton’s 2nd Law for Rotational Motion to find the angular acceleration:

{{\tau }_{net}}=I\alpha \Rightarrow \alpha =\frac{{{\tau }_{net}}}{I}=\frac{MgR}{0.5*M({{r}^{2}}+3{{R}^{2}})}=\frac{2gR}{{{r}^{2}}+3{{R}^{2}}}

Since linear acceleration can be found from angular acceleration multiplied by the radius of rotation (R):

 a = \alpha R = {{2g{R^2}} \over {{r^2} + 3{R^2}}}

Finally, since we’re looking for the ratio of the dropped height to the unrolled height:

{H \over h} = {g \over a} = {g \over {{{2g{R^2}} \over {{r^2} + 3{R^2}}}}} = {{{r^2} + 3{R^2}} \over {2{R^2}}} = {3 \over 2} + {{{r^2}} \over {2{R^2}}}

This conflicts with the results from Noschese’s class, where they derived \frac{H}{h}=2+\frac{{{r}^{2}}}{{{R}^{2}}}, however, their demonstration based on their results is very convincing.  Let’s take a look at the difference in ratios using the two derivations:

For a toilet paper roll of inner diameter .0095m and outer diameter R=.035m (our school rolls from the janitor supply closet):

\frac{H}{h}=2+\frac{{{r}^{2}}}{{{R}^{2}}}=2+\frac{.0095{{m}^{2}}}{.035{{m}^{2}}}=2.074 \frac{H}{h}=\frac{3}{2}+\frac{{{r}^{2}}}{2{{R}^{2}}}=1.5+\frac{.0095{{m}^{2}}}{2*.035{{m}^{2}}}=1.54

It appears that our discrepancies aren’t just differing mathematical representations of the same formula, but that we have a significant difference in our derivations.

In looking over our assumptions, we assumed no air resistance, and also that the unrolling toilet paper roll rotates about its outer radius (is this really true)? I wonder what assumptions were made in Noschese’s class that may account for these differences. It will be interesting to get his class’s perspective on the problem, and provides a great practical study for our students of different approaches to a problem, and the importance of understanding the ramifications of assumptions made in beginning a problem solving exercise!

Update: it appears our calculations are correct.  Check out our high-speed video confirmation!

Slow Motion Toilet Paper Falling