rallain | May 12, 2010ScienceBlogs.com is running "Ask a Science Blogger". The basic idea is that you, the reader, get a chance to ask questions to us, the bloggers. You can either post a comment in the link above or send an email to .
I would like to go ahead and answer one of the questions already posted. nemski asks:
How big does the world appear to an insect?
I like this question because it can be answered at different levels. First, what do you mean by world? If you mean "the Earth", then the answer would be that the Earth essentially appears the same to an insect as it does to us humans (from a size…
rallain | May 10, 2010This is a question that comes up every now in then. But I would like to ask a few similar questions with my first order approximation answers. I would love to hear some other ideas on these questions.
Do people need a functional understanding of math to function in this world?
I say no. Maybe this is not a popular answer, but this is my first answer. Let me give my reasons. What percent of people in this world have a functional understanding of math? (let me just say functional understanding means they can do basic word problems and understand what is going on) If I estimate this…
rallain | May 8, 2010I have one more comment about the previous MythBusters episode where they compared two cars crashing into each other at 50 mph vs. one car crashing into a wall at 100 mph. At the end of the episode, Jamie reflected on the experiment. He said something like (regarding how he incorrectly thought one car at 100 mph was the same as 2 at 50 mph):
"....that was a mistake. You know what? I am ok with that. That is how you learn stuff"
What a great attitude. I think this is something many students miss out on. Which is better, taking a class where you know everything and don't even need to…
rallain | May 6, 2010I already mentioned the MythBusters' crashing two cars episode where they correctly doubled the speed of a pendulum type object. Overall, this was a very visual (although expensive) demo. There was one part that left a sour taste in my mouth - the final explanation from the narrator. First, they showed this.
And then they had an explanation that went something very similar to to this (after restating what the sign above said)
"Although the two-car crash doubles the speed, the energy the crash is transferred to twice the mass resulting in a crash that looks like just one car hitting a wall…
rallain | May 6, 2010In the last episode of MythBusters, Adam and Jamie wanted to test something that Jamie had said earlier:
"Two cars crashing head on at 50 mph is the same as one car crashing into a wall at 100 mph"
Jamie was wrong, but that is not what I am going to talk about. Instead, I am going to talk about Adam's small scale test of this situation. Really, it was a nice set up. Basically, he wanted to collide something into a wall at one speed and then double that speed. Then he was going to collide two things together at the lower speed. He had a cool way of measuring the collision. He put a piece…
rallain | May 5, 2010I was going to make this as a video tutorial, but it just didn't work out right. So, here it is in blog post form.
How do you deal with a video that zoom and pans at the same time? You could keep on adjusting the coordinate axis AND adjust the scale for each frame - but sometimes that is not possible. Tracker Video has a great tool to handle these types of videos - the calibration point pair. The basic idea is that you identify two points in a scene that should be stationary (part of the background) and track those two points. Tracker will then adjust the coordinates and scale to make…
rallain | May 4, 2010Really, I have many jobs. But in this case, I am talking about my two jobs inside my one job as learning facilitator. I like to call myself a learning facilitator rather than a teacher or a professor because I can't make people learn (that would be teacher). Professor would imply that I am professing the truth. Well, I don't know if anyone knows the truth in science - I am sure I don't. So, I am going to stick with learning facilitator (LF).
In my official role as a LF, my institution has actually assigned two jobs:
Help students learn (my words, not theirs)
Evaluate students'…
rallain | May 4, 2010So you have seen these color filters (or gels as they are also called). When you look through a red filter, everything looks red. What do they do to the light? I am not going to tell you the answer. However, I will show you some examples so that you can figure out the answer yourself.
In this video, I am going to use a red and a green laser pointer. The nice thing about laser pointers is that they essentially create only one color of light.
rallain | May 4, 2010It is my duty as a blogger to mention lasers in this time of international laser celebration. This May is the 50th anniversary of the first lasers. Everyone knows a laser that they love, right? We all use them. So, instead of talking about lasers, I am going to post some great links to other laser stuff (including some of my stuff).
the history of the first lasers (AIP)
The above is the American Institute of Physics's presentation of the history of the laser. Really, this does a great job of giving all the details you would want. I highly recommend it.
Uncertain Principle's Laser…
rallain | May 3, 2010This video seems like it is getting popular, but maybe that is because it is so awesome.
Maybe it is just me, but I find this video very visually satisfying. I love the way they compare the different runners.
Anyway, there is some physics here. Commenter Ben sent me the link to this video (thanks!) with some great questions. Which of the runners has a greater kinetic energy? What about the power? These aren't too difficult to answer, but the first thing is to get the data. There are several options (including just using a stop watch). But no, that is not good enough for me. Instead, I…
rallain | April 28, 2010Normally, it isn't really news when a show doesn't do anything wrong. I am making an exception for ESPN's Sport Science. Here is part 2 of Sport Science trying to reproduce Kobe Bryant's "jumping over a car" stunt.
And here is part 1 (although part 2 is the only interesting part). See. I can get along with Sport Science. Anyway, I am not sure that Kobe's jump used wires - but I assumed it was fake. Here is my analysis of Kobe's Jump (this stuff is old). And this is the plot I created from video analysis of Kobe.
The tough thing about looking at Kobe's jump is that he changes his body…
rallain | April 28, 2010You see in my experimental determination of the location of the accelerometer in an iPod, I used two different iPhone apps. Let me briefly mention some of the free iPhone apps that give you acceleration data.
AccelGraph: This is one of the apps I actually used. What do I like about it? Well, it can record x, y, and z acceleration data and then you can email it to yourself. What could make it better? How about a timed start to record (like start recording in t seconds) and a preset record time. This would allow you to set up your experiment and get your iPod set up before you start. As…
rallain | April 27, 2010There are several free iPhone-iPod Touch apps that let you look at the acceleration of the device using the built in accelerometer. I was planning on reviewing some of these free apps, but I didn't. When I started playing around with them, it was clear that I needed some way to make a constant acceleration. There are two simple ways to do this - drop it, or spin it in a circle. I decided to go with the circular motion option because I like my iPod and because Steve Jobs told me to.
While playing with this, I realized that the acceleration depends on the distance of the sensor from the…
rallain | April 26, 2010I meant to mention this earlier since it happened a little while ago. There is this "mini-conference" with three schools: Southeastern Louisiana University, Southern Mississippi University, and the University of South Alabama. The purpose is to give students (and some faculty) a chance to present their work at a smaller conference. I really enjoy this, mostly because it is small and I get to see lots of undergrad talks. There are two talks that stuck in my head.
Dr. Jiu Ding "Dynamical Geometry: From Order to Chaos and Sierpinski Pedal Triangles"
Jiu Ding is a mathematics professor at…
rallain | April 24, 2010Check this out.
So, the guy jumps from 150 feet into some cardboard boxes. Why are the boxes important? You want something that can stop you in the largest distance to make your acceleration the smallest. Here is my Dangerous Jumping Calculator. Basically, you put in how high you will jump from and how much distance you will take to land and it tells you your acceleration.
You will probably need this G-force tolerance info from wikipedia.
One problem - this calculator doesn't really work for this case. It doesn't take into account air resistance. Does air resistance even matter in this…
rallain | April 22, 2010I would just like to take this post and use it to promote some relatively new blogs that I like. Speaking of blogs, I think I have classified blog posts into 3 different kinds.
Link aggregators. Chad at Uncertain Principles does this with his Links posts. These kind of blog posts are the glue of the internet. It actually turns out to be important for people to somehow determine what is worthwhile and what is not. The problem is that any old fool can put stuff on the internet and sometimes only an expert would know it is crap. Link posters may not always be experts, but as a whole they…
rallain | April 22, 2010I wasn't paying attention. Earth Day is today. If I would have thought of this before, I could have done something awesome. Instead, here are some reposts related to the Earth and energy. They have been sitting for a while in my post-compost, so they are nice and smelly.
Most of these deal with Earth-type stuff and energy.
Rotation of the Earth as an energy source. What if we could some how use the rotational energy of the Earth? How much would we have to slow it down to get something useful?
Solar Powered motorcycle - possible? There was this story about an electric motorcycle that is…
rallain | April 21, 2010I want to give ESPN's Sport Science another chance. The segment on Tim Tebow didn't really have any errors. I thought, cool - what about this one on Jason Pierre-Paul? Here is the clip. Oh wait, embedding is disabled. Ok - if you want to watch go here (the image is a link)
The goal of this segment was to examine why Jason is so awesome at tackling. The answer: because he can do flips. Really, that was the answer. Let me briefly go over some of the problems with this segment.
Correlation does not mean causation
They didn't say it explicitly, but it seems the are saying the reason he…
rallain | April 19, 2010You probably already know how I feel about the "media" and their physics explanations (see attacks). Let me summarize the problem. There are a whole bunch of cool shows on tv that deal with sciency stuff - that is good. These shows then try to teach some science along with their demos and explosions and stuff. This is also good. However, they usually butcher the explanation part. Some of them (ESPN's Sport Science) must just literally make stuff up that sounds cool.
I understand that in common usage, things like "force" can be used lots of different ways. I am ok with that. Also,…
rallain | April 16, 2010If you have been on the internet, you surely have seen this website showing the sizes of different starships. Way cool. Here is a small sample - but it doesn't do the site justice. You really need to go browse around.
Of course, I can't let something like this just go. One of the things I always think is interesting is to consider objects of different size. Perhaps the general idea is that you can just scale stuff up or down as you like. But, it doesn't work this way. Let me start with my own spaceship. It is a sphere with a thruster on the back. It just holds one person.
Now, what…