rallain | January 31, 2010This is really random, but quick. I was channel surfing and saw the end of the movie: Fantastic 4 - Rise of the Silver Surfer. SPOILER: At the end someone really big explodes in space. There, that wasn't too much of a spoiler, was it? (unless you read the title)
I know I am a loser. I initially thought: wow, that seemed pretty fast for that scale. I wonder if that exploding stuff was going faster than the speed of light. OH! I know, I will use Tracker to measure it. It is video that is set for analysis since it has the Earth in there - and I am pretty sure I know how big that is.…
rallain | January 30, 2010After judging the science fair last week, I would like to revisit my tips for you the science fair participant.
Warning number 1
Some of the things I say here might go against what your teacher has told you. I am not sure what you should do in this case. Your teacher gives you a grade and I am just some dude on the internet. Proceed at your own risk.
Oh, and maybe you are a teacher. I think that is great that you are seeking more tips for your students. However, note that I have not read any science fair rules. I am merely thinking about science fair projects from a science viewpoint.…
rallain | January 27, 2010Here, I am referring to Dan Meyer's "Be Less Helpful" mantra. I like it, but maybe you aren't familiar with Dan. Here is his take on a high school physics problem. Or maybe you would like the video version:
Be Less Helpful - CMC North 2009 - Dan Meyer from Dan Meyer on Vimeo.
What does this have to do with Reddit? Check out this comment posted in physics. Basically, someone is asking for help finishing physics homework by that night. I really like the following two comments. First, another user said:
"This might help you in the short term, or for this course. But it won't in the long…
rallain | January 27, 2010This is actually been sitting around for a while waiting for me to post it. Here is another short Christmas-toy demo. I am going to pull this yo-yo at different angles and on two different surfaces. Check it out.
What is going on here? Let me look at the first case where I pull the yo-yo and it slides without rolling. Here is a diagram.
Normally, I would just say - "hey - a free body diagram". And this is one, but you have to be careful. Normally, a free body diagram treats an object as though it were a point mass. You can't do that in this case because you have to consider rotation…
rallain | January 26, 2010This is one of my favorite things to do in class. I don't do it too often, or it would lose its specialness. Probably the best time to do this is near the end of class.
I pass out half-sheets of blank scrap paper. Students are told to write a question on the paper and turn it in. The question can be about anything. Or maybe it could be a statement about something that was covered and is still confusing. I tell the students not to put their name on it.
I collect all the questions (or statements) and pick some to go over in class. Usually, I get some off the wall non-sensical type…
rallain | January 25, 2010There is a question that keeps coming up in discussions I have. "What should elementary students study in science?" Probably the best answer to this question is: something other than what they are doing now.
What do I think students should know about science? Should they learn how to calculate kinetic energy? Should they learn the difference between mass and weight? These things are important building blocks for other ideas, but sometimes it seems like there is a lot of focus on these building blocks and no focus on science. Just talking about kinetic energy is not necessarily science.…
rallain | January 22, 2010Since my previous post on R2-D2 flying was so popular, I thought I would follow it up. I was going to add these two points in the comments, but a separate post seems to make more sense.
Point 1 - R2 flies at a constant speed
Well, he obviously doesn't always have to fly at a constant speed. However, in the clip I was looking at there are two important things in the analysis. What angle is R2's thrusters at? Is R2 flying at a constant speed? I found a much better quality version of the flying R2 from Billy Brook's site. That helped out a lot. So, on to Tracker Video Analysis (I always…
rallain | January 21, 2010You know I can't help but like Star Wars. Even with the new stuff, I watch it. Recently, I was watching the Clone Wars cartoon and noticed something odd about the way R2-D2 flies. I know what you are saying...."the odd thing is that he flies at all. Why didn't he fly in episodes 4-6?" Who knows. Here is the best image I could get of R2-D2 flying (from wookieepedia).
What is wrong? Well, maybe you can't tell from the image I posted. Here is a diagram of flying R2-D2.
If R2 (I can call him that because we are good friends) was flying like that, why would that be a problem? That would…
rallain | January 20, 2010I stumbled on this flash game Bloons. The basic idea is that you (the monkey) throw these darts and try to pop some balloons.
Well, what is the motion of these darts like? Is it constant acceleration? Time to pull out the free and awesome Tracker Video Analysis.
I threw a few shots and captured the screen with Mac OS X's quicktime X (which does screen recordings now). Then I chose a few of the motions to analyze. I was going to use Tracker's autotracker feature, but I am not sure how well it would work since the dart changes orientation (of course I didn't even try this to see if it…
rallain | January 20, 2010It is not exactly finished, but I have moved over all of my old posts from my previous site. If you want to browse, feel free to look at the archives. Some of those are not too interesting, so I will just list the pages with the most views (but I will leave out my 12 reposts from Christmas).
The physics of Michael Jackson's moon walk
Development of the atomic model
Mythbusters: bringing on the bullet drop
Giant water slide jump
Physics of the water rocket guy
That should be enough to hold you over for a little bit. I still have not fixed all my tags for these posts, but that will come with…
rallain | January 19, 2010Today is show-n-tell day (at least for this blog). Our department (Chemistry and Physics) has recently been focusing on increasing our undergraduate enrollment. One of the steps we have taken is to have the following video created. I think it is pretty good.
Southeastern Louisiana University Chemistry and Physics from SELU Chem and Phys on Vimeo.
If you are a chemist, the first thing you are going to say is "what is up with the green bubbling liquid?" You are right, that is fake. Sometimes these video people want stuff that looks cool.
rallain | January 19, 2010My dad and I had a disagreement. We were driving back from a trip and he let me take over the wheel for a while. His complaint was that I was driving too slow and it was driving him crazy. For me, I thought I was driving fast. My typical behavior is to drive 3 mph under the speed limit. That is just how I roll. In this case, I knew he wouldn't be able to handle this so I went the speed limit (70 mph).
Here is the problem. The speedometer said 70 mph. The gps thingy said the average speed was 69 mph. I think my dad feels that the gps is correct and that cars have speedometers that are…
rallain | January 14, 2010Here is a picture of something you have seen before.
These are two pictures of the same location in my house. The one on the left is taken when the Sun was up outside and the other one when it was dark outside. For both pictures, I had the same lights turned on inside. So, why does it do this? Why can you see stuff outside when it is bright outside, but you don't see a reflection of the stuff outside? Why when it is dark outside, does the opposite happen? You know what I am going to do next, right? Diagram. Here is a diagram for when it is dark outside.
The person can see the blue…
rallain | January 14, 2010If you know me, you know I love Tracker Video Analysis. Basically, it is a free-java program that allows you to get position-time data of a moving object from a video. In Tracker version 3.10, there is now the autotracker feature. This will automagically mark the location of an object moving in a video. How do you use it?
First, the video. This is a video I made of a plane landing at an airport. Not much exciting going on, but that never stopped me before. I put this video on vimeo instead of youtube because vimeo allows you to download the original video.
Landing Airliner from Rhett…
rallain | January 13, 2010Check out this picture.
These camera flashes are just awesome (well, they look awesome). They are not a very useful thing for pictures in this case. Here is the problem. Well, first here is what the flash on a camera is supposed to do. Suppose there is a camera and a ball in a dark room. In order to get light to reflect off the ball and be detected by the camera, you need light. The flash is that light. You can think of it like a flashlight that is only on for a moment. It doesn't need to be on for long since it doesn't take very much time to get an image.
Notice that I drew red…
rallain | January 12, 2010I hate to be left out. ScienceBlogs, Starts with Bang has started a fitness theme that we are encouraged to participate in. I like to participate. I even had some good ideas. Here is what I was thinking:
Look at the physics of Wii-fit (actually, this one is good, I should come back to it someday)
Energy and forces involved in a push-up
Blogging push-up challenge - where I do a push-up for every 10 visits to my blog each day for a week (my estimation is that this could end up being dangerous - or maybe safe)
The physics of the gymnastics kip move. This one IS on my todo list since my two…
rallain | January 12, 2010In a MythBusters episode some time ago, Adam and Jamie jumped off a building. There was some cool stuff in this, but I want to focus on the acceleration data they collected. Before jumping into a pit of foam, they first wanted to test the set up by dropping a dummy into it and measuring the accelerations. Lucky for me, they showed a quick screen shot of their data. Note: I previously posted the calculations for jumping and stopping off of a building.
For me, I see this and think - numerical integration. Before that, let me look at the physics. Here is a diagram of someone jumping off a…
rallain | January 11, 2010I am totally ready to get back to blogging. In fact, I have a post that is 3/4th complete that I have been working on since before Christmas. Anyway, in order to procrastinate a little bit more I would like to share two learning observations (maybe they are not really about learning).
Kids these day
First, I was in the airport. When I am sitting around starring at the walls, I can't help but accidentally overhear someone that is 4 feet away. So this guy was talking about how impressed he was with kids these day in school. They are learning all sorts of stuff that he had already forgotten…
rallain | January 4, 2010This is great. Many people have already reported google's apple-dropping homepage in honor Newton's birthday. In case it disappears, here is a screen shot.
So, I got this awesome note from Dale Basler. He said that his class had analyzed this falling apple animation. What a very Dot Physics-y idea (check out his analysis). He said they were questioning the results which might be due screen capture issues. I decided to reproduce this.
I captured the motion with Apple's Quicktime X screen recording feature. I then used Tracker Video Analysis - which now has an autotracking feature that…
rallain | January 3, 2010Wow. In xkcd 681 comic, there is an impressive illustration of the common term "gravity well". Here is a small part of that large image:
I can't resist. I must talk about this awesome illustration. My goal for this post is to help someone understand that comic (although the comic itself does a pretty good job).
Energy
Energy is the key here. Here, I will talk about two types of energy - kinetic energy and field energy. In this case, kinetic energy is basically just the energy associated with something moving. Field energy is the energy stored in the gravitational field. You could…