rallain | May 27, 2010
You should check this out - its free. This is a very creative take on some of the ideas of physics. Think of it as physics meets Dr. Seuss, but with more detailed art work. Created by James Dunbar, it is quite fun to read. Of course, there are some things that are always exactly correct - but that is true of everything, right?
BANG! The book website (sorry, I forgot the link earlier).
rallain | May 27, 2010Sometimes (ok - just once) I get asked for recommendations about reading material on the ideas of teaching physics. I used to recommend Arnold Arons book on teaching introductory physics. Still, that is a classic and a great resource. However, there is a better one.
Teaching Physics with the Physics Suite - Edward Redish
Originally, this was kind of like the instructor's manual that went with one of the big name intro-physics books (maybe the new version of Halliday and Resnick). But this book is way more than an instructor's manual. What is even better is that it is online and free (see…
rallain | May 27, 2010Even though I have taught courses like this before (in a sense, my last physical science course was like this), I really don't like these courses. I will classify a "tell and repeat" course as one where the instructor tells the students stuff and then the students repeat this on the test. Look around, it happens a lot. But really, what is the point?
Here are some example questions from a tell and repeat course (most of these I have used in a course - when you point a finger, 4 are pointing back at yourself):
What is the difference between a meteorite, a meteor, and a meteoroid?
Which has…
rallain | May 27, 2010I don't know why they call it a tail drop. Here is a video:
The link I clicked that brought me to this video said the equivalent of "OMG!" That is not what I thought, really I am not sure what is so impressive (except that he didn't fall off the skateboard). If the original poster was impressed with the height of the fall, he clearly has not seen the 35 foot jump into 1 foot of water by Professor Splash.
Anyway, it seems like a simple video to analyze with Tracker Video Analysis. Mostly because the camera is stationary, there is little perspective problems and the motion of the object is…
rallain | May 26, 2010I am still thinking about the Red Bull Stratos Jump. Sorry, but there is just tons of great physics here. Next question - how big of a balloon would you need to get up to 120,000 feet?
I am not going into the buoyancy details of Archimedes Principle - I think that was covered fairly thoroughly with the MythBusters floating lead balloon. However, in short, here is a force diagram for a floating balloon.
For a floating balloon, the buoyancy force must equal the weight of the whole thing. It turns out that the buoyant force is equal to the weight of the gas (or fluid) the object displaces…
rallain | May 25, 2010I was at the zoo this weekend, it was fun but hot. Somewhere near the middle, there was a sun dial.
The cool thing (well, I think sun dials are cool anyway) was that the shadow was pointing about to the "12". I looked at my watch and it said 1:05 PM. What is up with that? The answer: Daylight Saving Time.
What does noon traditionally mean? In this day of the digital watch, most people associate noon with 12:00, you know - lunch time. But before clocks, noon referred to the time of day where the Sun was at the highest point in the sky. It is not too difficult to find this time. Just…
rallain | May 25, 2010A note about the end of the semester (I really should have posted this a few weeks ago): sometimes I get students that come in and say they are not happy with their grade. It is not unusual for them to come in right before the test, but it seems more common to come after all the grades are finished. Here is a typical student:
"I really need a C (or D) in this class, but I have a 67%. Is there anything I can do to bring my grade up? Maybe I could do an extra project, or file some papers or wash your car?"
That is not one real student, but I have had students ask if they could file my…
rallain | May 24, 2010While I am still fresh on the Space Jump topic, let me take it to the extreme. Star Trek extreme.
SPOILER ALERT
But really, is this a spoiler alert if it is from the trailer of a movie that has been out forever? Of course, I talking about the latest Star Trek movie where three guys jump out of a shuttle and into the atmosphere.
So, in light of the Red Bull Stratos jump, how would this jump compare? First, my assumptions:
This Star Trek jump is on the planet Vulcan. I am going to assume this is just like Earth in terms of gravity and density of air.
The jumpers in Star Trek have on stuff…
rallain | May 24, 2010Crazy, but I was on CNN Saturday night. They contacted me at the last minute to talk about the Red Bull Stratos Jump. Here is a screen shot to show that I am not making this up (or that I have awesome photoshop skillz).
Looking back, maybe I looked like an idiot. Really though, it wasn't my fault. I thought we were going to talk about physics. The first two questions threw me for a loop. Here are the two questions and my response (roughly paraphrased):
Will Felix survive the jump?
Answer: I guess so.
Is there a scientific reason for this jump?
Answer: I thought we were going to talk…
rallain | May 20, 2010I am going to try to answer another Ask a ScienceBlogger question. This one is from George P. Burdell. He asks:
"If the universe is expanding from the big bang, has anyone tried to reverse plot the galaxies to figure out the exact point where the big bang occurred?"
Actually, he asked two questions, but I am just answering the first. Second, let me note that I am not really a cosmologist - so I am just making up answer.
In short, the answer is that everywhere is the center of the universe. Think of it this way. Imagine that there are only two dimensions and these two dimension are the…
rallain | May 20, 2010And there's parliament. Ok - sorry, I had to make a "Tom (Swans on Tea)" title for this one. Tom, forgive me.
Here are two great circular motion videos. First, this one is from Dale Basler. He made himself a fine little floater-type accelerometer. Better than just make it, he made a video of the accelerometer in his car going around a round about. Check it out.
Bobber Meets Roundabout from Dale Basler on Vimeo.
So, if he is driving at a constant 10 mph, how big is the round about (traffic circle)?
Next video - more silly kids
First, I saw this one on ZapperZ's Physics and Physicists who…
rallain | May 20, 2010Grades are all over the place, but what are they? Well, I guess there are a few questions. What is a grade? What is the grade supposed to be? Why do we give grades?
I think the grade is supposed to be a measure of a students' understanding of the material. Probably everyone would agree with that description. But, it is still a bit tricky. Who (or what) determines what a student should understand? Who determines what an "A" means? Fortunately, there is not a governing body (yet at least in physics) that says what an "A" grade means. It is left up to the expert evaluations of faculty…
rallain | May 19, 2010A new video from the Red Bull Stratos Jump guys came out. Here it is:
This reminds me of an unanswered question about the Stratos jump that I didn't address on my last post on this topic. Commenter Long Drop asked about how much Felix would heat up as he falls from 120,000 feet. This is a great question. The first, off the bat answer is that he won't heat up too much. Why do I say this? Well, when Joe Kittinger jumped from over 100,000 feet and didn't melt. Still, this is a great thing to calculate.
How do you calculate something like this? I will look at this in terms of energy. For…
rallain | May 17, 2010Grades are in. So, let me just say a couple of trends that I saw on the physical science final exam.
Gravity on the moon
I asked the question: "why is the gravitational force on an astronaut less on the moon than on Earth?"
The simplest answer is that the gravitational field on the moon is smaller than on Earth (I would accept that answer). Why is this? It is because the moon as a much smaller mass even though it also has a smaller radius (that idea is rather complicated for this class - that gravitational force depends on both mass and radius). I would also take "the mass is smaller" as…
rallain | May 17, 2010And lo and behold. Another semester has ended. I was going to post about somethings from my physical science course (for non-science) majors. Then I noticed that both Ethan at Starts With a Bang! and Farady's Cage posted about their semester reflections. I vote that the academic blogging community make this a tradition.
This semester, I had 3 courses. Here is a brief overview of what I learned.
Physics for Scientists and Engineers II
This is the electricity and magnetism part of the intro physics course. As I said before, I used Matter and Interactions (Chabay and Sherwood). I am not…
rallain | May 17, 2010Galactic Binder (a Star Wars fan site) invited me to write an article for them. Obviously, I said "yes". But what to write about? I decided to write a different version of my flying R2-D2 post. What is different? In my original post, I go into a lot of details. Essentially, that post is like most of my other ones where I am thinking out loud. I used to work out the answer and then write the post, but I like it this way better.
Here is the Galactic Binder post:
Aristotle, Newton, and R2-D2
So, in this Galactic Binder post, I don't go into the details. Basically, I just use the flying…
rallain | May 16, 2010I am excited. This Wednesday, the MythBusters are doing the giant water slide jump. Maybe you are new to the internet and you haven't seen this video. Here it is:
And since it is as old as the hills, of course I have already analyzed it - actually twice. First, the video is fake - but it is an excellent fake. Here is another site with details on how this was created.
What did I look at in my previous posts? Here is a summary.
The video is difficult to analyze because of perspective changes.
Even with these problems, nothing says it has to be fake. The vertical acceleration during the…
rallain | May 15, 2010I was going to just leave the oil spill in the gulf topic alone. Not because it isn't important, obviously it is. Rather, I wasn't going to do anything because I didn't really have anything to add to the topic. After a couple of readers requested it, I think I do have something to add. How exactly do you estimate the amount of oil flowing into the gulf?
What do I have to start with? A video. Here is a video of the undersea oil leak.
Now, I am not the first to estimate the oil flow rate (NPR on Purdue Prof's estimation and here a commenter make a quick calculation). Like I said, I am…
rallain | May 13, 2010Yes, green laser pointers are cool. Especially when you use them to make stuff fluoresce. Ok, what about a blue laser pointer? They are getting surprisingly cheap (Amazon has a 10 mW for pretty cheap). Still not cheap enough for me. But, you know what? Some of the physics majors here at Southeastern Louisiana University purchased a couple of these. Physics major Daniel let me borrow his.
First, they don't look too bright. This is probably because our eyes are not too sensitive to this wavelength. The blue 10 mW does not look anywhere near as bright as the 5 mW green that I used in…
rallain | May 13, 2010Yes, I am going to talk about the MythBusters latest duct tape episode. A couple of pre-post points:
They call it "duct" tape. I call it duck tape. It doesn't work very well with ducts. Also, it is good for water proofing stuff - you know like a duck. For the rest of this post, I am calling it duck tape. (Wikipedia agrees there is some naming problem)
You know I love the MythBusters - right? I hope you don't think I sit around waiting for them to make a mistake so I can pounce on them (I save that for ESPN Sport Science). In this case, they just made a small mistake. A mistake that…