Physics

Please complete the following AP Problems for class on Monday (or Tuesday if there’s a snow day).

• Problem 1 – Omit part (c)
• Problem 2

• Heat & Temp: p.389 (17)
• Ideal Gas Law & Kinetic Theory: p.439 (16, 34)
• PV Diagrams: p.476 (99)
• Electric Potential: p.599 (16)
• Electric Field: p. p.569 (31)

Some electricity problems: p.568 (12, 18, 19, 23, 27, 33, 37)

I want to give you an AP Problem too. That’s here. (It’s a short heat one. Do it!)

Have a great weekend.

Do this AP Problem from 2009. (Yes, Allison, you should do it too.)

Here is the second video. (Click to go to YouTube.) If you thought the last one was funny, then you’re going to love this one. This one is also shorter at a little over 6 minutes.

If you want to print the slides for your notes, they are here.

“Chugga chugga choo choo! Time’s up!”

These videos from Rutgers should help you solidify your understanding of waves and their properties. As you watch the videos remember that you can move the video frame-by-frame using the right and left arrow keys on the keyboard. Because each frame lasts the same amount of time, counting frames is a good way to get time data when you need it.

• To answer number 2, watch this video.
• To answer number 4, watch this video.
• To answer number 5, watch this video.

I would also like you to think about other kinds of oscillating motion, like masses on springs and pendulums.

• Does the amount of initial stretch (the initial amplitude) change the period of oscillation? Watch this.
• Does the amplitude of a pendulum change the period of oscillation? Watch this.
• Does the length of the pendulum change the period of oscillation? Watch this.

At long last, the video lecture is complete. A few things about the video:

1. It’s relatively short and to the point. (14:26)
2. If you want a paper version of the slides for your notes, those are here. (PDF)
3. I say “If you think about it” too often. Sorry.
4. Little Morrills are playing with Legos in the background.

Click here to go to YouTube and watch the video.

And I also promised HW. Click here for an AP question for you to do at home. We will correct it in class and I will collect it. We can discuss exactly how I will count the grades for you, keeping in mind that the goal of an assignment like this is to give you practice and experience with AP problems so that by the time we get to the test you will have tried a wide variety of AP problems.

As always, email with questions.

As promised, here are my responses…

1.) Why did you sign up for AP Physics?

Since starting at JSR six years ago I’ve been interested in teaching AP Physics, mostly because of the challenge it provides to both the students and the teacher. I appreciate a good challenge. I started the AP Physics program two years ago when the school asked me if I would be willing to give it a try.

2.) What do you hope to get out of this class?

Teaching AP Physics allows me to work with students who are both talented and interested. At least I assume that is your disposition if you’ve signed up for an AP class. Students like you challenge me to think about ideas more deeply, and I enjoy that.

3.) What have you heard about this class?

I have mostly heard that the class is difficult, but I have also heard that students enjoy coming to class and enjoy learning about the way things work.

4.) How comfortable are you with being confused?

I haven’t always been comfortable with being confused, but I have come to see confusion as an essential part of the learning process. If you aren’t confused when you’re learning something, it probably means you already know it. We will all need to work on being comfortable with confusion so that we can work through it. Last year most students handled the confusion aspect of class very well and I heard very little complaining. I hope to see that trend continue this year.

5.) What do you do when you don’t know what to do?

I’ve heard problem solving defined as what you do when you don’t know what to do. After all, if you knew what to do there wouldn’t be a problem. So how do I solve a problem? I try something: draw a picture, make a graph, write down what I know. I Start. If you read a problem and you don’t immediately know what to do, sitting there and staring at it won’t help. Start working. Start coming up with a plan. If you get stuck and you come see me for help I want to hear you say, “I tried this and this and this and here’s what happened. What should I try next?” Simply saying, “I have no idea what to do!” will rarely help you solve a problem or learn.

6.) What are one or two things that you, as a student, are planning to work on next year? How are you going to do that? (So you know what I mean by goals, here is an example. As a teacher one of my goals next year is to conduct more labs and hands-on activities in class. Your goals might be related to skills or they could be something more attitudinal, like trying not to get frustrated.)

One of my biggest goals for this year is to make inquiry a bigger part of AP Physics. In short, inquiry is students conducting experiments of their own design to answer a question they they came up with on their own. This is very difficult because student-directed inquiry is very time consuming and we don’t have a lot of time. My goal is to focus our effort on the concepts and topics that are most important and eliminate any topics that are not essential for the AP Exam in May, thus freeing up time for you to conduct experiments in class.

7.) What grade are you planning to get in this class? What grade (1-5) are you planning to get on the AP exam in May? How are you going to do that?

You should be able to achieve a 90 or better in AP Physics if you are willing to work for it. It will not be easy, but it is not impossible. Most student’s grades fall between 80% and 93%.

On the AP Exam most students earn a passing grade of 3 or better. UNH will give you credit for Physics 401 if you score a 3 or better; they will give you credit for Physics 401 and 402 if you earn a 4 or 5. JSR has offered AP Physics B for two years now and the scores break down as follows:

2 people scored a 5
6 people scored a 4
11 people scored a 3
2 people scored a 2
0 people scored a 1

In other words, 90% of the JSR students who have taken the AP Physics B exam are eligible to earn some college credit at UNH. Actual awarding of credit will, of course, depend on your specific school and major. Talk to me in class if you have more questions about getting credit for your work.

8.) I will probably assign at least an hour of regular homework every class. This homework is going to be a really important part of you learning how to do physics. How are you going keep up with this work?
I will do all of the homework I assign. I need to so that I can answer your questions thoroughly. You also need to do all of the homework. Refer to #5. You must genuinely try every problem. Leaving it blank and asking me in class will not help you learn. You have to try something, even if it doesn’t work.

9.) Give me your reaction to this idea: I’m not going to grade your daily homework, but I still expect that it will be done well and done thoroughly. (This is something I’m considering for next year but I haven’t come to a final decision yet.)

I should note that I did not collect or check homework last year. The people in class who worked hardest on homework even though it was not collected ultimately had the highest grades in the course.

10.) What are the one or two things that I could do next year that would most help you learn and work to the best of your ability?

I could give you the usual teacher list of things a good student does. You’ve heard it before. I think if I had to narrow my focus to three things they would be: Be Interested, Do the work and Keep it positive.

11.) Is there anything else I should know about you as a person or a student?

I will refer you to a great article in the Boston Globe by a writer named Jonah Lehrer. The article is called “The Truth about Grit.” The article debunks the idea that greatness comes solely through natural ability. Mr. Lehrer argues that, in reality, people who achieve great things have to work really hard at it.

The first example of this that the article describes has to do with Isaac Newton, a man whose ideas we will spend about half the year talking about. The mythology surrounding Newton describes him as a super-genius who saw the universal truths of physics in a flash as he sat beneath an apple tree. Mr. Lehrer points out that that just isn’t how it went down…

Unfortunately, the story of the apple is almost certainly false;Voltaire probably made it up. Even if Newton started thinking about gravity in 1666, it took him years of painstaking work before he understood it. He filled entire vellum notebooks with his scribbles and spent weeks recording the exact movements of a pendulum. (It made, on average, 1,512 ticks per hour.) The discovery of gravity, in other words, wasn’t a flash of insight – it required decades of effort, which is one of the reasons Newton didn’t publish his theory until 1687, in the “Principia.”

In case you aren’t good with math 1687 – 1666 = 21 years of work. The more time I spend learning and teaching the more I believe that being smart isn’t even half of the battle. I urge you to take a few minutes to read the whole article and tell me what you think in the comments (first names only please).

Bowling ball drop data:

Frame #: Ball Position
Frame 0: 2.4 m
Frame 4: 2 m
Frame 6: 1.75 m
Frame 9: 1.25 m
Frame 10: 1 m
Frame 12: 0.6 m
Frame 14: 0.35 m

Find a the velocity as accurately as possible for as many points as you can given this data. Remember that there are 30 frames per second. Also, think about this: What would you need to be able to determine the velocity more accurately?

(Note: All positions are approximate, but frames 12 and 14 were especially hard to estimate.)

I made a short video, as promised, which you can see here. Someone pointed out to me that I stapled a couple pages in the wrong order in the packet, so the video also explains the correct ordering of the pages. Still have questions? Email me.

The packet is due on the first day of class, though I would prefer to hear from you before the end of summer with your answers to the survey questions.