Still looking for something fun this summer?

One of the most mind-boggeling, thought-provoking, get students to completely change their conception of thinking, math and more, is

Godel, Escher, Bach.

And best of all MIT has created a free class based on this book, complete with lectures, notes and more.

If you undertake this journey, the rewards will be immense, and you'll certainly have your mind blown more than once.

March 1st

The big idea for today that as the radius of a planet increases, its centripetal acceleration decreases. Also, the acceleration of the earth divided by its radius squared is almost the same as the acceleration of the moon. I think.

Friday, February 26

Today in class we had a double period that consisted of meetings with Mr. Burk for about 25 minutes about the projects, and working on them while other groups met. The big idea for projects is looking ahead and finding something new to master.
Hw:6d and webassign, work on project

Scribe is Mary Elizabeth

last wed class

First we took a blast from the past energy re assessment , and then we talked more about the moons lab, and finally we worked with the vandegraf generator.

Important ideas were that objects will repel each other when on the vandegraf and that to linierize the orbital period vs radius, you need to raise the radius to the 1.5 power.
next scribe is Burge.

2/22/09

Today in class we went over 6c and did a problem in class.

The problem was with a square where one side has a length of 0.5 meters and all the charges are equal and are +or- depending on the charge of the point and is equal to 50*10^-6:

1)Find Fe on 1

2)Find E at location of i

3) Find any place(s) where the electrical field vector is 0

4)Find E at A

5)What force would a -20muC charge feel at A?

DYLAIN scribes next

Class on 2-17

Today we worked on our projects. Homework was 6c. The next scribe is Paxton.

Class 2/16/10

Today in class we talked mostly about Coulombs law. Coulomb's law is basically an equation that states that Fe=(k*q1*q2)/r^2. We also learned that constant K always equals 9*10^9. Using this information, we can find Fe as long as we know the charge of 2 objects and their seperation distance!

1.) If we find out the net charge of an object and divide it by the charge of an electron (always 1.6*10^-19) we can find out how many excess electrons there are.

2.) Also, one atom has an area of 4*10^20 so if we divide the area of the object by that number we get how many atoms there are overall.

If we divide (1) by (2) we can find how many electrons were transferred when the object was charged! yaaay..

(I tried to keep it short and sweet :]) next scribe is Joe!

Hard problem 4

Hard problem 4 has arrived.

Give it a try. Have fun, and ask questions.

Happy Valentine's Day--seeing hearts

Here's a really cool video that shows just how much we are pattern seeking animals. We can find hearts anywhere.

2/8/10 class!

Today we reviewed the ideas of 6A and then checked 6B which led to us talking more about polarization. There wasn't a main idea of the class today but I guess I will talk about a problem in 6B that will help with understanding polarization more. In 2b in 6B to get equal opposite charges:

1. touch the two spheres together
2. rub the paper to the plastic making it have a negative charge.
3. bring the negatively-charged plastic to the spheres but don't touch them
4. the charges in the spheres will separate and the positive charges will go into the sphere closest to the plastic because opposites attract and the negative charges will go into the sphere farthest away from the plastic because the same charges repel.


5. Separate charges and spheres

2/2/10 Class

Today, we wrapped up kinetic and potential energy and began our exploration into electrostatic force.

We finished off Chapter 5 with one last problem involving a bungee jumper jumping off a cliff. Using the given information, we had to calculate various things such as the max velocity, the point of max velocity, and the spring constant of the bungee cord. The big insight used to solve this problem was realizing that . Using this, you can set to find the spring constant of the bungee cord and through that the rest of the answers.

After a short break, we began our journey into the wonders of electrostatic force with a hands-on experiment involving "magic" tape. We put layers of tape on the desks and quickly ripped the top layer off and observed the way this top layer of tape interacted with its surroundings (i.e. other pieces of tape, paper, etc.). When two top tapes came in proximity with each other, they tended to repel each other, demonstrating a new type of force: electrostatic force. Other properties of the tape we observed was that it attracted pieces of tape from the bottom, rather than repelling them. Mr. Burk also showed us similar interactions between a plastic rod and paper as well. This energy comes from the displacement of electrons in the objects being rubbed together; when electrons (which are negative) are lost or gained, the charge of that corresponding object becomes more positive or more negative. When two objects have opposite charges, they will attract each other.

That's what we did in class today. Next scribe is Margaret.

Big idea for Feb. 1, 2010

Today's main topic was applying energy to the motion of a roller coaster car as it goes along the track and does a loop-de-loop. Mr. Burk presented us with a problem requiring us to apply energy transferring, centripetal motion, and FBD presentation to solve.

The drawing for the problem is this:



The problem that Mr. Burk presented us with is as follows:
1) Find the speed of the car at points A, B, C, and D.
2) Find the minimum speed to make the loop.
3) Find the minimum height the car was dropped from to make the loop.
4) Construct an FBD for points A, B, C, and D.

The answers are as follows:
1) a. V=0 because the object is at the top of the course.
b. all of the Ug the car started with has now transfered into K
so mgh=.5*mv^2
v=square root(2gh)
c. the equation is the same except the height is now h-R
so v=square root(2gh-2gR)
d. the equation is the same except the height is now h-2R
so v=square root(2gh-4gR)
2) the centripetal acceleration is v^2/R and acceleration is Fnet/m.
so Vmin^2/R=mg/m
Vmin^2/R=g
Vmin=square root(Rg)
3) for the car to make the loop, the velocity at D squared is equal to mg/g*R because of the fact that the centripetal acceleration equals the def. of acceleration (see #2)
so 2gHmin-4gR=gR
2gHmin=5gR
Hmin=2.5R
4) the FBDs and diagrams for the car are below:

That is the entire insightful problem. HW: e-mail proposal to Mr. Burk and work more on the energy packet. Next Scribe: Timothy!!

You CAN change the world

Never doubt that a small group of thoughtful, committed, citizens can change the world. Indeed, it is the only thing that ever has.

--Margaret Mead

Boy, 7, raises $240,000 for Haitian Relief.

Tonight's (1/25/10) Homework

Hey guys, I was having a little bit of trouble with 2c (see how Kinetic Energy vs. Distance Fallen graph and Gravitational Force vs. Distance Fallen graph help to define Gravitational Potential Energy). I feel like Gravitational Force and Gravitational Potential Energy are kind of the same thing... I'm kind of confused about the difference between the two/the 2c question in general if you couldn't tell already. Anything would help, please comment! Thanks so much!

Hard problem 3

Hard problem 2 is dead——if you helped solve it, be sure to claim your propsicle.

Hard problem 3 can be found here.

An important point about 5C

A very important point came up today when a few students were discussing 5c. The question was which of the following two graphs is the right answer. It turns out the bottom graph is right. Why?

Hard problem, still not quite solved...

It's begging for you to finish it off... Have mercy...

Hard problem

Big Ideas from 1/20

We discovered big understandings from force vs. displacement graphs and energy vs. position graphs. The area in a force vs. displacement graph is work. The work done by the spring force is - 1/2(k) (change in x)^2.
Energy depends on displacement, and a large displacement leads to a large energy. A small displacement leads to a small energy. For the kinetic energy vs. displacement graph, the total energy was constant. The difference between the total energy and the kinetic energy is the potential gravitational energy.

Class on Friday Jan. 15th

In class on Friday we talked about how to go about solving energy problems. Mr. Burk gave us some steps:

Guidelines For Energy Problems

1) Start by defining a system

2) Give symbols meaning (ex: instead of looking at a symbol like K and thinking of it as just K, think of it as change in kinetic energy)

3) Do everything symbolically

Also in class, we talked about power.

Also,

Power is measured in Joules per second or Watts. 1 Joule per second=1 Watt

Homwork is to finish 5C

Monday's scribe is... Jason

Today in class...

Today, we started class by discussing how a single point particle can be thought of as a piggybank. and money as a whole is considered energy. i thought that was a cool analogy!!

Energy is put into an object, but then it must leave the object at some point. if more energy is put into an object than the amount that leaves, the object is gaining energy. if more leaves an object, it is losing energy.

Then, we looked at our graphs. K should be between 400N/m and 800N/m. The force of the spring is opposite the stretch. Just as a review: work equals force times change in displacement. (W=F*change x)

Homework is to finish 5b and start 5c. tomorrow's scribe is Sana!!

Blog Post 1/12

First off I would like to take the opportunity to thank Dylan for his choosing me, as I am really excited about talking about today's Big Idea...

That aside, Today's Big Idea is talking about the change in Energy being the same as Work done by the Surroundings and other factors (to be determined later). First off we discussed the SPP, or Single Point Particle which essentially labels one object in a system as a single point. Some things to remember about the Single Point Particle. First off, Single Point Particles only have K or Kinetic Energy. A good way to think about a Single Point Particle is like a rock. The surroundings (The Earth) does work on the Rock (Makes it fall). Therefore energy is transferred from the Earth to the Rock. Positive work for the Rock and Negative Work for the Earth.
Also we discussed the next sort of system separate from the Single Point Particle System. We can call this a multi part system. Basically this type of system includes multiple objects. To take our rock example further we can say that the rock includes both the Rock and the Earth. This way we can more effectively observe the LoCoE (Law of Conservation of Energy: energy is neither created nor destroyed, it simply changes forms). The energy although moving inside the system does not change overall for the system in relation to outside surroundings to the system. This is key in remembering that all energy is transferred between systems.

Those are the two basic big ideas. If anyone has any specific questions they can just post a comment below and I think I'll be able to answer them. Next scribe is Eliza.

class today

Class today.
Short and sweet

Big Idea: Today we looked at the different types of energy relating to gravity and weather they are positive or negative depending on the scenario. We also talked about weather or not our system should include one point or multiple, and how this effects the system and the energy we need to look at.

tomorrow, Rahul is the blogger

SAT II practice questions

Here's a link to some SAT II practice questions from the college board.

SAT II practice questions

You should see a number of questions are quite easy and quickly answerable:
In particular #5, 6, 12, 21, 22, and 23 are all easily within your grasp.

With a little effort, you should be able to use what we're doing now to do problem 11 and 15.

Most of the rest, will be covered throughout the year, with the exception of the problems on optics, which we probably won't get to—-this is why you need a book to study from.

Here are some other resources:

Sparknotes SAT II physics


SAT II Wikibook--not that helpful

Cracking the SAT II: one of the better SAT II review books, but none of them are great. All you really need are lots of problems.

As always, I'm happy to help you dominate the SAT II, but it's up to you to create the plan that will lead to success.

homework for tuesday

Be sure in addition to 5A that you also read and answer some of the questions from your classmates:

5.1 and 5.2 Questions

Burj Dubai Base Jump

Two basejumpers just set the world record for BASE jumping from the world's tallest building the Burj Khalifa (formerly called the Burj Dubai), from a height of 828 m.

Check out the video below:


Two questions:
1. Why didn't this video take the 13 seconds you calculated take an object to fall to the ground?
2. What was the average velocity of the skydiver? How does this compare to the velocity an object falling only under the influence of gravity would have when it hit the ground?

Hard problem 2

Someone tore through the last hard problem very quickly (I added a bit to the end). This is incredible work. Whoever did this should certainly count it as a FARMIP, and anyone else should try to do it themselves as a FARMIP.

Here's another problem.

Good luck.

your questions from the reading

Hi Guys,
I hope you're enjoying a relaxing snow day. I've put all your questions together into a wiki page below. I think it would be a good exercise for us to try to answer these questions together as a class.

In order to edit the questions, you'll need to create a free account with pbworks.

5-1 and 5-2 Questions

If you can take a moment or two to read over these questions, and if you have some ideas, offer an answer or two, that would be terrific.

Also, if you haven't sent me your questions yet, please do so.

Class on 1/6/10

The big idea from class today was the big idea of energy, it is neither created nor destroyed in a given system but it only changes form. We demonstrated this through the analysis of Net force, change in position, mass, and change in velocity. After simplifying the equation, we found if kinetic energy goes up, interaction goes down, which shows the change in energy but none is lost.

Next scribe is Dylan

the physics of snow

Since it's on all our minds....

Why does snow make everything seem much quieter?

Can it get too cool to snow?


Designer snowflakes from the lab

Physics of snowbaording (don't expect to do much of this tomorrow).

Another hard problem

Here's an idea if you're looking for something fun and challenging. I've posted a hard problem to google docs:

Hard problem for fun and challenge.


Give it a shot. It's a google doc, so you can just go and write questions, or try to sketch a FBD.

Study Hacks talks about deliberate practice

Another awesome blog post on why just working at something doesn't always make you better. You have to practice in a deliberate way.

What a study of chess experts teaches us about building a remarkable life

Some highlights:

What is deliberate practice?

It’s designed to improve performance. “The essence of deliberate practice is continually stretching an individual just beyond his or her current abilities. That may sound obvious, but most of us don’t do it in the activities we think of as practice.”

It’s repeated a lot. “High repetition is the most important difference between deliberate practice of a task and performing the task for real, when it counts.”

Feedback on results is continuously available. “You may think that your rehearsal of a job interview was flawless, but your opinion isn’t what counts.”

It’s highly demanding mentally. “Deliberate practice is above all an effort of focus and concentration. That is what makes it ‘deliberate,’ as distinct from the mindless playing of scales or hitting of tennis balls that most people engage in.”

It’s hard. “Doing things we know how to do well is enjoyable, and that’s exactly the opposite of what deliberate practice demands.”

It requires (good) goals. “The best performers set goals that are not about the outcome but rather about the process of reaching the outcome.”

Now here's the kicker—since deliberate practice is so hard,

Unless you’re a professional athlete or musician, your peers are likely spending zero hours on DP. Instead, they’re putting in their time, trying to accomplish the tasks handed to them in a competent and efficient fashion. Perhaps if they’re ambitious, they’ll try to come in earlier and leave later in a bid to outwork their peers.

But as with the intermediate-level chess players, this elbow-grease method can only get you so far.

That's right—most students, athletes, aren't doing anything close to deliberate practice.

What do you think will happen when you start doing deliberate practice?

A puzzle

In the interest of improving the blog, here is a puzzle that I found in the New York Times. Some of the questions it poses are relevant while others require more background knowledge than we have. A word of caution: it uses Tom Cruise and Nicole Kidman as examples. All the same, here it is.

When Tom and Nicole were in love, they apparently exchanged a pair of Oscar-type statuettes of each other made of solid gold. After their break-up, these former symbols of love became symbols of pain. To ease the pain, Tom Cruise hit on a stategy of “placating density.” Sorry, that should read “placating destiny.” You have to take an object that you associate with the loved one, and submerge it in the middle of a lake. If the water level rises, it symbolizes that your mental tide has turned, and it helps you to move on.

1. So, as shown in the figure, Tom Cruise took the solid gold statue of Nicole Kidman, rowed to the middle of a lake, and tossed it overboard. Did the water level rise, fall, or stay the same when the statue sank to the bottom, relative to the level when the statue was in the boat? Why?

1. a) What’s wrong with the path of the tossed statue in the figure?

1. b) It turns out that in his haste, Tom Cruise ignored another cardinal tenet of the metaphorical remedy. It seems that to get the full mental benefits, you cannot toss the pain-associated object. You have to release it gently with your hand still in contact with it when it touches the water. Can you think of a way that Cruise could have done this so that the water level rose when he released the statue in the middle of the lake and it sank to the bottom? (Note: The lake is too large for him to stand at the shore and drop the statue in the middle.)

There were two more metaphorically significant activities that Tom had to do, in order to erase the pain of the break-up.

2. The second task is termed “overcoming meanness harmonically.” Tom had to wear Nicole’s ring and run a specified distance as fast as he could on a windy day. Then he had to dash back the other way, returning to his starting point. The condition he had to satisfy was this: his average speed on the two dashes, which both had to be done the same day, had to be higher than the fastest average speed that he could achieve if there had been no wind. “No problem,” thought Tom. He waited until he had a strong wind behind him, ran the distance and then ran right back. His fastest speed without the wind was 25 feet per second. With the wind behind him, he achieved 30 feet per second. On the way back, his speed was 20 feet per second. What was his average speed? How could he have done this right?

3. The third task is called “outsmarting frictional resistance.” Tom had to take an object associated with Nicole and toss it as high as possible into the air. Then he had to catch it as it fell down. The speed with which it was falling had to be higher than the speed at which it was thrown.

Now it is clear that if an object is thrown up at a certain speed and then it falls down under the influence of gravity, its speed when it reaches the point from which it is thrown will be exactly the same as on the way up if there were no air resistance. However, in real life, air resistance causes a frictional force that is proportional to the object’s speed at every point. On the way down, will the actual speed of the object at the starting point be the same, or higher or lower than it was on the way up? How can Tom Cruise satisfy the third task?

here is the puzzle online

The science of Avatar

Here are a few posts that describe the physics of the movie Avatar. In your lifetime, scientists have already discovered hundreds of extrasolar planets orbiting stars throughout the Milky Way (the first extrasolar planet was discovered in 1992).

The science of Avatar

Pandora could be a reality

More science of Avatar

Curious about how we discover extrasolar planets? Here's how.

You can even play a game to discover them on your own.