Reflection on Buggy Lab

I can't seem to figure out how to do problem 6 on the buggy lab. It asks to write an equation for the position of the buggy at any time using x(position) and t(time). Anybody know how to solve that problem?

The Big Bang Explained

Ever wonder what the big bang is all about? What a multiverse is? This 2 minute video gives a great explanation by physicist Janna Levin, who is also a fantastic author. She wrote How the Universe got is Spots, and the award wining fiction book, A Madman dreams of Turing Machines. Both are great, quirky reads.

How to study for a physics assessment

Ok, so if you check the course calendar, you'll see that you have your first assessment in physics coming up next week. How should you study? Read carefully for my step-by-step guide to demonstrating deep understanding

Big picture of what you're doing:

1. Get out your copy of the Major Concepts for Unit 1. Read these through, and circle anything that seems completely unfamiliar to you.
   
2. Remember the purpose of this assessment. I am looking to help you see how well you understand these ideas. You can help yourself tremendously, by figuring out, before the test, how well you understand these ideas and making sure you master them.
   
3. While you study, your job should be to find/create problems that test these major ideas, try them, and then trouble shoot your work until you master the concept.
   

Step by step of what you should do:

1. Get a bunch of blank sheets of white paper or graph paper (if you're making/interpreting graphs).
   
2. Copy problems that we've done in class, on homework, and on webassign onto a a sheet of paper (one problem per page). Don't copy your answer from class notes.
   
3. Try to figure out which of the Major concepts this problem is testing, and write that at the top of the page.
   
4. Solve the problem. Try to do it in as much detail as possible. If you get stuck, write out a sentence explaining what you don't understand. The check the solution, and finish the problem. Recopy this problem and put it back into your stack of problems you're working on.
   
5. Keep working through problems until you've successfully mastered one or more problems from each topic.
   
6. Check yourself for small errors, like omitting units, writing bogus numbers, calculating slope as x/t, etc. Make a note of these on the problem, and focus on not making this mistake the next time you solve a similar problem.
   
7. If you can't find a problem from your notes or homework, this is a sign your understanding of this topic is incomplete. You can find additional problems in the text, or online by googling for them. You can also email me.
   
8. If you get stuck on a problem or concept, you are welcome to email me or schedule some time during backwork or a free period. But I also encourage you to use the blog to help increase your understanding as well (see below).
   
9. When you're done, you should have a small booklet of 10-20 problems that clearly show mastery of each topic.
   
   In practice, this doesn't take nearly as much time as you might think. With five days between now and the assessment, you can spend 10-15 minutes working out problems for 3 concepts per night, and have covered all 11 concepts by Monday night, giving you Tuesday night to go back over any last remaining concepts you're slightly unclear on.
   
   

   Using the class blog to ace a physics test

   
   If you find yourself stuck on a particular concept or problem, I encourage you to use the class blog to help you find the answer. Just create a new post (label it "reflection") and describe your problem "I can't see how to solve problem 2.4," or "I don't know how to draw a position vs time graph from a velocity vs time graph." Doing so will do a number of things:
   
   
   
   1. Just explaining what you don't know will often lead to greater understanding.
      
   2. You writing about a problem will help your peers to these themselves on what they understand.
      
   3. You will be contributing to the class community, and this will positively impact your grade (both intangibly and tangibly).
      
   
   
   Likewise, if you know the answer to a question posted by a peer, I encourage you to comment and leave a response. This will positively influence your grade.
   
   More tips:
   
   1. The science of studying, from Study Hacks

The art of taking notes in science class

Have you wondered exactly how you should take notes in physics to achieve the deepest understanding? You're not the first to ask the question, and not surprisingly, the author of Study Hacks has a few things to say about the art of taking science notes.

Notice that this post talks about going over your notes, but not just re-reading them, instead, it suggests you work to recopy/add to your notes so that you can develop a set of notes that can re-teach you the material in 10 years.

This can be a LOT of work, and I would encourage you not to do this for everyday we take notes, but if there's a time when we're covering something that seems particularly difficult, it might be a good exercise to try to go back and recopy and improve your notes.

Here are a few more tips from a college professor of geology.

day 3

today in class we used a photogate to measure how long it took dominoes set up at various distances apart from each other, to to fall a certain distance predetermined by the distance between each domino. We set the dominoes up at distances 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 centimeters apart.

Physics 8/27/09

Today in class we continued with our discussions of calculating velocity using graphs. We also did a lab using a sonar device that could measure where we were in relation to it. We then used it to calculate our velocity by walking from it and back towards it from distances of 2.5 meters and 1 meter. We moved at an almost uniform speed which meant that the slopes on our graphs were also uniform and were almost straight lines.

Tripp is our next blogger.

Beautiful time lapse of Persied Meteor shower

Sometimes, physics begins with just admiring the beauty of the world around us. Check out what you see if you spend a night taking photos of the sky during the Perseid meteor shower. To get a explanation of what you're looking at, check out the always great, Bad Astronomy. Be sure to click on the HD link to see this movie in all its glory.

Corrections Policy

Hi All,
Thanks again for a great class! I want to explain things a bit further on my offer of corrections.

In general, I will allow you to correct just about anything in this class. Under the following conditions:

1. You seriously should consider whether you need to do the corrections. I know this is hard, but you should ask yourself "am I doing this to raise my grade, or show I really understand an important idea?" If it's to raise your grade, I would suggest that you consider not doing corrections. You will have many, many grades in this class (more than 100 a semester, in all likelihood), and one 2/4 or even a 0/4 will have almost no effect on your final grade. Seeking perfection is a recipe for unhappiness and lack of sleep.
2. Ask yourself if you have time to do corrections. If you aren't getting 8.5 hours of sleep per night, or you're behind in something else, you probably should focus on those things first. They will have a bigger impact on your grades and happiness.

If you decide to do corrections, follow these rules:

1. Turn your corrections in within a week after the assignment (unless you make arrangements with me).
2. Re-do the ENTIRE assignment. Do not simply copy your old work--do it again, with fresh eyes.
3. When you get to parts that you missed, you should ALSO write an EXPLANATION OF WHAT YOU DID WRONG (this is essential for credit).
4. At the end of your assignment write a note specifically stating EVERYONE and EVERYTHING you collaborated with. You are forbidden from looking at another student's work if you are doing corrections. Omitting someone/something you collaborated with constitutes an honor violation.
5. Turn in both your old and new assignment. If it seems like you copied your old work, I might not give back all the points you missed.

That's it. I reserve the right to modify this policy for specific assignments, or rescind it altogether if it is being abused.

8/26/09 Class Notes

In class today, we used the ticker timer to find the average velocity of the buggy. The velocity of the buggy is uniform. The ticker timer makes 60 dots per second. We used the ticker timer and a ruler to find the the time and distance between the dots. In order to find the average velocity, you must divide the distance by the time (change in x by the change in t). The average velocity was 0.7 cm / 0.016 s = 43 cm/s. 43 cm/s * 10 s = 4.3 m. Velocity = 43 cm/s and change in time = 20 seconds round-trip. How far did the buggy travel in total? (v * change in time) = 43 * 20 = 860 cm. We also discovered that distance = (change in time / 2) * velocity or
distance = (velocity * change in time) / 2.

If you read one thing today...

Make it this excellent post at study hacks about how to create a unsinkable organization system. Do this now as a 9th grader, and watch your grades soar through high school, college and beyond. It really is that simple.

Tuesday's Class

In class today, we measured the speed of a toy car. First, we measured the time it took for the car to go distances of 0.5, 1.0, and 1.5 meters. Then each group had to make a prediction for what the speed was going to be if we ran a trial of 2.0 meters using the previous data and setting up an equation. You had to get the slope of the information. The change in meters over the change of time. My group found that our prediction was correct and our actual results were only milliseconds off. We then measured how long the car has been traveling at different times. We found the average velocity of the car by getting the slope of the graph. We then wrote an equation to find the position of the car at any given time. This was the same equation as the slope formula. Lastly, there was a problem to find out how long it would take the car to get from Atlanta to San Diego, which is around 3,000 miles. It would take a really long time.

A physicist writes an opera!

The connections between science and art are too numerous to list, but this has to be one of the coolest and most unique I've seen. Lisa Randall, a physicist at Harvard who is researching extra dimensions and how gravity might be 'leaking' into hidden extra dimensions was asked to write a libretto (musical text) for a completely new opera. The video below features Professor Randall talking about her work. It's definitely worth watching.




You can read more about the opera here.

Space Probes and Messages to Other Civilizations

In class yesterday, we talked about Pioneer 10, a space probe launched in 1977 to explore Jupiter, Saturn, Uranus and Neptune, and that has now left our solar system. We also discussed that Pioneer 10 contained a plaque featuring a series of pictures designed to communicate a message from humankind in case the probe should be encountered by extraterrestrial civilizations. You can click on the image below to get a larger image.

In class, I said that Pioneer 10 was the furthest man-made object from the earth. This is untrue. That record is now head by the Voyager 1, a space probe launched a few years later. Voyager was able to pass Pioneer 10 thanks to a number of gravity assisted speed boost from passing close to the outer planets.

In addition, Voyager contained the golden record I mentioned in class that contains a message for any extraterrestrial civilization it might encounter.

You can listen to a wonderful story about the creation of this record told by Ann Druyen, widow of the great scientist Carl Sagan, whose idea it was to make the record in the first place. This story is part of the incredible Raidolab podcast, simply one of the very best shows you can listen to on your ipod.



Voyager 1 also plays a central role in the original Star Trek movie, which is a pretty funny look back to a young William Shatner 1970s imagining of the future.

So what would YOU put on a record to extraterresterials? Here's a podcast with answers from comedian Margaret Cho, composer Phillip Glass, Chef Alice Waters, and authors Michael Cunningham and Neil Gaiman.

Top 10 ways to know the earth is not flat, and 10 more cool things about the earth

So you've just finished setting out write in your own words why the earth is not flat. This can be a challenging assignment, because you often want to say "because it's so", or "because of gravity, the seasons, or time zones." These are all good starts at the question, but take a moment and read this post for some comparison.

Do you notice that the author tries to build logical arguments to explain why the earth is not flat? Check out how the author carefully reasons through experiments that demonstrate the earth is round...

If the earth were flat, then two sticks at different locations would produce the same shadow. (premise)

But, when this experiment is carried out, the shadows aren't equal. (experiment and evidence)

because the shadows aren't the same, we conclude the earth is not flat. (conclusion)

This type of writing is the hallmark of scientific reasoning. It doesn't simply tell the reader what we know, it tells the reader how we know.

While you're at it, check out 10 things you don't know about the earth, a fascinating post from the fantastic bad astronomy blog.

And of course, the earth is round, but technically, it's an oblate spheriod.

Also, you might want to check out the flat earth society website, notice how their explanations are filled with scientific sounding terms and explanations, but most of this is just jargon intended to confuse the reader. Compare it to the 10 reasons the world is not flat essay, and you can clearly see the power of science and the value of clear scientific writing. Wikipedia also has a nice article on the flat earth society.

Finally, here's the link to the BBC story on the flat earth conference.

Thursday's Class

On Thursday, we practiced and decided what we were going to do in the Domino Lab. At the start of class, we experimented with the photogates and tried to guess what they are used for. It turns out that they are used to time something. As a class, we decided that the distance between dominoes determines the speed of falling dominoes. We also came to the conclusion that we needed to measure the spacing between the dominoes, the distance for the entire rally, and the time it took for the rally to complete. The class agreed the speed equals distance divided by time. We then practiced setting up the dominoes at different distances apart and testing how long it would take to pass through both gates of the photogate. In order, to do this the photogate needed to be on pulse.

Idea for the day

How is this an appropriate metaphor for our (mine and your) relationship in this class? Comments welcome.

HT (hat tip)-Dan Meyer, teacher extraordinaire.

Get Ready for the Grand Adventure

Welcome to Physics!



I hope that this image of the Saturn V (still today, 40 years later the world's most powerful rocket and complex machine) puts you in the right mindset for the adventure we're about to embark upon in this class. This class should be filled with thrilling moments, moments where you take risks, discover ideas you previously never knew, correct misconceptions you've been carrying around for years, and see the wonder of the world around you. Of course, like any astronaut will tell you, there are sure to be some scary moments from time to time, but with hard work, careful preparation, teamwork and communication, there are no limits to what we can accomplish. I'm thrilled to be your captain/mission control on this journey, so let's strap in and get started!