Physics

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!”

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.

Click here for the circuit simulator.

Your assignment tonight is based on a course called “Physics for Future Presidents” at Berkley. The course and text are by Dr. Richard A. Muller. You may either read a portion of the text for that class or watch the video of the course lecture. Links and instructions for each appear below.

Note: After watching the video on my drive home, I think the reading is probably a better use of your time and definitely more applicable to what we’ll be talking about in class, so I’m scratching the video option. My apologies. The professor rambles on a bit too much for it to really apply to what we’ll be doing tomorrow.

1. Read the Text. Click here for a PDF or here for a web page. Read through the section titled Hybrid Autos.
2. Watch the Video. Go here and then watch Lecture 1. Skip ahead to the 50 minute mark. (You could also click here to go directly to the iTunes Music Store and download the video for use on a video-capable iPod. Once you reach the yellow course page go to the “Fall 2009 Video” tab and get the first lecture.)

The reading and/or the video will help to inform a project that we will be starting and I want everyone to do this assignment. I’m counting on you to complete the assignment. There may be a quiz in class on Tuesday.

If you have any trouble let me know before you come to class by email.

Use these links for today’s virtual lab activity.

Part I: Diffraction
Part II: Interference
Part III: Diffraction and Interference

Here’s the problem from class today. Thanks to Jess for taking the picture and emailing it with her ultra-small (definitely NOT a cell phone) laptop. Answers to follow later this evening.

(Click the image to see a full-size version. Angela – clicking is accomplished with the left mouse-button.)

As promised, here are my responses…

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

Since starting at JSR five 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 last year 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. Interested in being challenged and interested in learning. 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 heard from students last year that they found the class difficult and often confusing. AP Physics is, as you know, a college physics class and I found most of my college science, math, and engineering classes to be difficult and often confusing.

That said, students also told me that they mostly enjoyed class and learned a lot.

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. I think if we can learn one thing from last year’s group it is that we should focused on working through your confusion rather than dwelling on it, if that makes any sense.

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 shifting the focus of the class from me (The Teacher) to us, the class as a whole. I hope to have you spending a lot of time in class thinking and working and not just taking notes. This means more labs, activities, investigations, and problems during class rather than lectures and notes.

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?

As most of you know, AP exams are scored 1-5, 5 being the top score. A score of 3-5 will generally earn you college credit. A 1 or 2 will not be accepted by most colleges. Last year all ten students took the exam and the class average was 3.7. Here’s the breakdown of their scores:

2 people scored a 5
4 people scored a 4
3 people scored a 3
1 person scored a 2
0 people scored a 1

As you can see, we did pretty well, especially considering the fact that it was my first year teaching AP Physics. I expect that we will do even better this year.

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.)

Homework is really important in this class. You need to work problems so that you can really struggle with the material and refine your ideas about how the physical world works. A portion of every class will be spent talking about homework problems, including student presentation of solutions. If you don’t do the homework you won’t do well in this class. Even so, grading homework seems to lead people to make up answers and copy from the various sources so they can show that they did their homework and get the grade. I’m 90% certain I won’t be grading homework this year. We’ll continue talking about this.

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 two things they would be: Do the work and Keep it positive.

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

I just read 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. Take a few minutes to read the whole article and tell me what you think in the comments (first names only please).

Only five people in class today. Wow. I hope everyone did well at their various competitions. Luckily we have three full blocks next week. One of those blocks will probably be a quiz.

• Today we finished Chapter 10 by talking about elastic potential energy. Those problems that I assigned way back when will be due on Monday.
• After finishing Chapter 10 we went right into Chapter 11 – Fluids. I made a couple hand-outs for you to look at… the brand new Chapter 11 Toolbox and a Chapter 11 Summary. Both are pdfs.
• I assigned some Chapter 11 homework which will be due on Monday as well: p.353 (7, 15, 18, 21, 33, 35, 40, 43, 59, 67)
• Monday will be a big homework review day.

For fun, you can read these Fermi Questions. (Note: this type of problem is named for Enrico Fermi.)

Email me if you need to.

I’ve been trying to think of a way to let you guys earn some extra toward your Newton’s Laws test. It needs to be something that makes you think about physics and something that doesn’t require too much time for me to grade (I’m just being honest). It would also be nice if your project ended up being something I could use in my other physics classes.

The first thing that comes to mind is a video, but that’s a lot of work. Given the amount of work required, any videos you turn in will be of a very poor quality. Again, I’m just being honest.

So the next thing that comes to mind is that you could create, perform, and analyze some kind of physics demonstration that relates to something we’ve done this year.

Here are some starting points:

• Physicists at Play – Read the suggested article (it’s a PDF) and look through the demonstrations.
• Physics Demonstrations by some guy dressed up like a magician. Remember: it’s not magic, it’s physics!
• UC Berkley Lecture Demonstrations
• Harvard University Physics Demonstrations

Project Requirements:

1. Demonstration must be well rehearsed and it should work. I know that things happen (believe me, I know) but you should try the demonstration at least once before class to get some practice.
2. You should be prepared to talk about what aspects of our study are illustrated by the demonstration. You should be prepared to take questions relating to the “physics” of the demo.
3. You should hand in a paper that describes the demonstration itself as well as the concepts it is meant to demonstrate. This should be typed and formatted like a lab report.

You may earn up to 10 percentage points to add on to your Newton’s Laws test. (The class average on that test was 65% and this would bring it up to 75%, which is more where it should be.)

Let me know if you have any questions.