Rhett Allain
rallain
Posts by this author
July 25, 2009
This is not really physics stuff. Well, it could be, but I am not going to take it that way. This is just a post that I consider to possibly add to the usefulness of the internet. When ever I want to do something, I always search online first. Suppose I want to make one of my dive lights into…
July 23, 2009
I am pretty sure this came up on some email discussion listserv. Someone mentioned that students could just look up the answers to homework on cramster.com. Maybe you are more with it than I am, but I had never heard of this. Of course I had to check it out.
At the basic level, cramster gives…
July 21, 2009
The Anacapa Society is a professional organization promoting research in all areas of theoretical and computational physics at primarily undergraduate institutions.
If you are at such an institution, I would recommend taking a look and perhaps joining. In my views, undergraduate research is one of…
July 21, 2009
Chad is posting some very useful stuff at Uncertain Principles. Basically, he has quite a few scientists that are not professors or such answering some questions. This is a great way for students to get a feel for what scientists actually do. If you don't subscribe to Chad's blog, you totally…
July 21, 2009
So, I built a new accelerometer. Why? The jelly-jar one was just not doing it for me. Plus, the cork was starting to make the water all yellowy. It was a good start, but I can do better. What was wrong with the jelly-jar one? First, it didn't let the cork move very far before hitting the wall…
July 21, 2009
This comes up everytime I teach physics for elementary education majors. The curriculum I use (Physics for Everyday Thinking - which is awesome) says that the colors in white light are ROYGBV (Red-Orange-Yellow-Green-Blue-Violet). Typically, I will get a student that says "Hey! What about indigo…
July 18, 2009
pre-reqs: vectors, kinematics
I haven't done a "basics" topic in quite some time. It's odd, I have used centripetal acceleration quite often, but I never derived the expression that I use. To get to the point, the magnitude of the acceleration of an object moving in a circle is:
Also, the…
July 18, 2009
Note to self: don't do the mechanical equivalent of heat lab again. It doesn't really work that well and there are better labs to do.
So, what is the mechanical equivalent of heat lab? It is actually a pretty cool idea. Take and object and drop it. What happens to the kinetic energy the object…
July 16, 2009
Yesterday, I uploaded a post from my old site about slowing down time to make videos look like they were on the moon. If you haven't read that, the short story is that it doesn't look right when speed Apollo videos up so that the acceleration is -9.8 m/s2.
What started that whole thing was an even…
July 15, 2009
Note: This is a repost from my old site. Time to move it over.
First, what is different about motion on the moon and on Earth? Since the moon has a smaller mass in spite of its smaller size*, the moon has a smaller gravitational field. The gravitational field on the surface of the moon is 1/6th…
July 14, 2009
This has been on my list for quite some time. Really, it must be since i posted about measuring acceleration in free fall with an iphone. So, this post will be all about accelerometers.
How does an accelerometer work? Really, an accelerometer measures force some way on a known mass. Let me show…
July 11, 2009
My friend J sent me a link to this gyrobike (http://www.thegyrobike.com/index.php). From what I can tell, it's a flywheel that you put in the front wheel of a bike. The site claims that this will help kids learn how to ride a bike.
So, what do I think? Clearly, this is a real product, but I am…
July 8, 2009
What do you see when you are in a completely dark room with no lights?
That is a great question to ask. It can bring out some interesting ideas. Anyway, here is an easy demo to show the color black. The basic idea is to build a box that has a small opening. Here is what it looks like from the…
July 6, 2009
July 4th can be fun. One activity my family enjoys is playing in the lake at my parents house. Along with this comes the jumping off the dock. Great fun, and great physics. Here is a short clip.
Work Energy Example from Rhett Allain on Vimeo.
Notice that I violated my own rules for making…
July 4, 2009
I created another screen cast showing how to get started with a numerical calculation for one of my classes. In this case, the students are attempting to model the motion of an object falling with air resistance. The following example doesn't show the steps including the air resistance, but maybe…
June 29, 2009
Slate's Explainer has an answer and question post about moonwalking. Here is one of the very good questions answered there.
Would it be easier to moonwalk on the moon?
The Explainer says "absolutely not" and attributes this to the awkwardness of walking on the moon. The article gives an example…
June 29, 2009
I finally saw the movie Hancock. Yes, I know it has been out for a long time but I don't get out much. You know me, I can't leave something like this well enough alone. It's not my fault, I was born this way. It shouldn't spoil the movie too much if I tell you this one scene (you have probably…
June 27, 2009
I have already talked about science and why everyone should take some science courses. The short answer (in case you don't want to read the previous post) is that everyone should take science because science (along with art and other stuff) is what humans do.
So, tomorrow I will be off to attend a…
June 26, 2009
Was the moonwalk fake? No, not the Apollo landings. I am talking about Michael Jackson's moonwalk. You got to admit, he had a big impact on a lot of stuff and this is my way to give him respect - physics.
I am sure you know about the moonwalk. Maybe you can even do the dance move yourself, but…
June 24, 2009
I made this screen cast for my algebra-based lab. Maybe you will find it useful also. This is a tutorial using Tracker Video Analysis (an awesome free program as I have said many times). In this tutorial I analyze a moving cart that shoots a ball up and lands back in the moving cart (called a…
June 24, 2009
The internet sure can bring some awesome stuff. Chad at Uncertain Principles has a great post about the vision of elves. He refers to a part of The Two Towers where Legolas can count the number of riders of Rohan from a great distance.
Not only is the post great, make sure you read the comments…
June 23, 2009
This was on my 'to do' list, but Tom at Swans on Tea beat me to it. Basically, this grocery store has these plates that when depressed produce electrical energy. Tom does a good job pointing out that this is not free energy (the original article says this also). Clearly, the energy comes from…
June 22, 2009
Note: This is an old post from the time before my blog was in wordpress. I noticed there was some incoming link for this, and I never moved it over. Here it is in it's unaltered (except for this part) format.
I don't know why I even suggest a new energy source. Fusion power is only a few years…
June 22, 2009
Maybe this isn't the best video to analyze, but it sure is funny. I am not sure why it is so funny - maybe you should just watch it first.
Sledgehammer Funby Stressmaker
I don't really know why these guys are putting explosive on sledge hammers. Sure it looks fun, but I think I would pass.…
June 19, 2009
I have been wanting to look at this whole curved bullet thing, but I wasn't sure how to approach it. In case you are familiar with the myth, this is from the movie WANTED (which I did not see). Apparently, some people learn how to make bullets curve by moving their gun. Here is a shot of a…
June 18, 2009
Ok, this is a post about a particular curriculum, in particular Physics for Everyday Thinking. Let me start with a story.
Some time ago, our college of education was going through an NCATE accreditation review. For some reason, they needed a science course that was just for education majors. As…
June 13, 2009
Our German friends let us borrow their son's bike after he got too big for it. I guess it will still be called a "bike" because it has two wheels.
See. No pedals. We don't need no stinkin pedals. Really, this is a great way for kids to learn how to ride. They just start off kind of walking…
June 12, 2009
Jennifer over at Cocktail Party Physics has a nice post about her trip to Disneyland. The one ride that would be fun to play with (in terms of physics) would be the tower of terror. Think of the cool things you could do with a video camera during that ride. It would be like a mini-vomit-comet.…
June 9, 2009
So, analysis of the movie Up is pretty popular in the blogosphere. Figure I might as well surf the popularity wave. So, I have a couple more questions.
The most important thing to estimate is the mass of the house. I am going to completely ignore the buoyancy of the house. I figure this will be…
June 5, 2009
Have you seen a cooler merrry-go-round than this?
Wow. A two-level huge merry-go-round with climbing ropes and everything. I didn't think you could have something like this in today's era of lawsuits. Man, the kids love this thing.