rallain | February 22, 2010My last Olympics post may have been a little complicated. I am going to try to make this one a little easier. In this post, I want to look at the landing portion of a ski jump. This could apply to THE ski jump, but there are some things in that even that make it a little more complicated (but I might come back to that in another post). For this case, I will consider the freestyle event - aerials. I didn't search too long, but here is a nice short video.
First, a quick estimation of how high they are "falling" from on the way down. In that video, the jumper takes about 1.5 seconds to get…
rallain | February 20, 2010The kind folks over at BloggingHeads TV were nice enough to offer me an opportunity to discuss some science stuff with Ed Grabianowski from io9.com. Here it is:
In this discussion, we talk about:
Learning physics and physics education research
The value of science educators
Good and not so good science on TV
Journalism and 'balance' with regards to science
Science fiction as a guide to the future
rallain | February 19, 2010Red Bull is sponsoring this sky dive from really really really high up - Stratos: Mission to the Edge of Space. Seems dangerous. The basic idea is that Felix Baumgartner will take a balloon ride up to 120,000 feet and jump out. Here are some questions:
Will he reach supersonic speeds?
The Red Bull site says: "can Felix react to a 35 second acceleration to mach 1?"
How about the claim that he will free fall for 5 minutes and 35 seconds? That seems pretty short.
In 1960, Joe Kittinger jumped from 102,800 feet. Will 20,000 feet make a large difference?
Assumptions
Clearly, this can be a…
rallain | February 17, 2010It is winter Olympics time and time for physics. The event that I always gets me thinking about physics is short track speed skating. It is quite interesting to see these skaters turn and lean at such high angles. All it needs is a little sprinkling of physics for flavor.
Check out this image of Apolo (apparently, it is not Apollo).
How about I start with a force diagram?
I know what you are thinking...Fcent....what force is that? Yes, I am going to use the centrifugal force in this case - but remember that sometimes fake forces are awesome. In short, if I want to pretend like Apolo…
rallain | February 16, 2010Do you need some physics to go with your beads? Well, here it is. Actually, I will let you do the physics (for now - meaning if you don't analyze these, I will).
Here are some pictures of a broken strand of beads. I hung them on my fence - you know, for display. Click the image to get a larger analyzable version. Oh - I just happened to include a meter stick in the image. Also, just for show I included a level (that is level).
Now, I have two videos. In both of these videos, I again included a meter stick. You know...because I like meter sticks. Also, I am posting these videos on…
rallain | February 16, 2010Now I get to do something with that force scale I built.
I had a request some time ago to talk about friction. Friction is surprisingly complicated. When two surfaces rub against each other, why is there a friction force? The basic answer is that the stuff the two surfaces are made of (atoms) are interacting with each other. If you like, you could think of the bumps on one surface hitting the bumps on the other surface. I know I said it was complicated and that doesn't seem to complicated - does it? The complication comes when you try to model this interaction by looking at either all…
rallain | February 14, 2010I was thinking about some experiments that deal with friction and I wanted to show something with a force probe. The problem is that most people don't have one of these. So, I decided to try and make one out of simple things. In this case, I am using some straws, a rubber band and some paper clips. Let me draw a little sketch of how this thing works.
The basic idea is to use the rubber band to measure the force (by measuring the amount the rubber band stretches). The two paper clips do two things. First, it allows you to hook up the device to something (like hanging some Lego bricks on…
rallain | February 13, 2010Do you like my title? I will make a connection in just a bit. This post is mostly about online colleges. I saw on TV that Kaplan now has online courses. So, what do I think about that? Here are some points.
Some people can learn online
I think this is an important starting point. Yes, there are people that can do just fine in an online course. Say there is an online course in physics (and there are). I think that students (not sure how many - could be a lot) that could perform just as well on a physics test as a student that took a traditional format course.
I don't think this is a…
rallain | February 11, 2010Do you have a green laser pointer? You should. They are relatively inexpensive now. What if you take your laser pointer and aim it at stuff in your house? The laser dot always looks green, right? This is actually a pretty important point about color. Suppose I have the lights on in a room and I look at a blue book. White light is basically all the colors of the visible spectrum, so a diagram like this might be appropriate:
So, the book looks blue (since that is what your eye sees). Note that I just showed blue light coming off the book, really the other colors reflect some too but…
rallain | February 9, 2010Forgive me for all the posts on ESPN's Sport Science (example: Pulling and Power). I can't help myself.
In the short episode recently, Sport Science compared a football player pulling a sled with huge tires on it to a truck pulling stuff. I think their goal was to compare the power per kg from for the player and the truck to show how awesome humans are (and let me just say that humans ARE awesome). The problem was that they really didn't give the truck a fair chance.
For the first test, they had Marshawn Lynch pull 585 pounds of stuff. The real question should be: how hard does he have to…
rallain | February 9, 2010Note: This is part of my ongoing attack of ESPN's show Sport Science. Really, I am continuing to look at the episode where they calculate a football player can produce 57,000 Watts by pulling some stuff. Wait...I don't want to limit my stuff to Sport Science. I see this stuff all the time. The problem is that people confuse the force needed to move something with its weight.
So, you want me to pull something? Great, I am a physics guy. I could probably pull maybe 100 pounds. That seems reasonable? But wait! I will increase it to 500 pounds! That is like two huge football players.…
rallain | February 8, 2010This came in the mail.
This is an ad for someone's online homework service (I am not saying who). The important part, that you might not be able to read, says:
"Make Learning Part of the Grade"
I think I can interpret this logo in two different ways. Both of these interpretations are not too helpful.
Isn't that what a grade is supposed to be?
Maybe you already know that I am not a big fan of grades (grades and obedience, the point of grades). So really, what is the purpose of grades? I think of a couple of things, but most people should be able to agree that they somehow (magically)…
rallain | February 7, 2010I would like to continue my attack on the show Sport Science - ESPN. In this short episode, they are comparing the power of NFL player Marshawn Lynch with that of a truck. You can watch it here if you would like.
There are two things that are not quite right with this episode, first, the power thing. I will save the friction problem for another post. So, if you didn't watch that clip, the basic idea is that Marshawn pulls some heavy tires. Sport Science then calculates the power needed to do this and then repeats a similar thing for a truck. Quick review. What is power? In short,…
rallain | February 7, 2010Looks like the show Sport Science (on ESPN) might take the place of Fetch! With Ruff Ruffman as the target of my bad-science attacks. Note: it looks like ESPN has the short episode I will be attacking online, so check it out.
Let me start off with the big problem (which The Onion already talked about). Why do you want to make a show about science that has really terrible science (if you can even call it science)? I really don't get that. If you want to just talk about cool sports stuff, do that. Please don't call it science. Ok. Now on to the particular attack.
In the last episode,…
rallain | February 6, 2010So, I put together part of my online textbook (finally). Let me give a little history and insight into this 'textbook'. Ok - I blog, I am sure you got that part already. When I write a post, I like it to start from the basic ideas so that anyone could find it and get what I am saying about some physics thing. Well, I started to realize that there were some things that I kept repeating (like how to add vectors). Instead of re-writing this every time a post had vectors, I made a post Basics: Vectors and Vector Addition. Then, I realized that I could keep doing this and slowly build up a…
rallain | February 5, 2010The following is a collection of some of my posts that can be put into a simple and quick textbook-type thingy. I am not really sure you would call this a textbook, but maybe you would. This does not include everything you would normally find in a traditional textbook, but clearly it is not traditional. I tried to keep it to just the fundamental ideas. As I write more stuff that is appropriate, I will add it.
In terms of the level of this material, I would think it would be appropriate for advanced high school physics or introductory college-level physics.
I plan to update this list with…
rallain | February 4, 2010Recently, I was talking about vectors. At that time, I had to stop and recall how I had been representing vectors. Ideally, I should stick with the same notation I used in Basics: Vectors and Vector Addition. But let me go over the different ways you could represent a vector.
Graphical
Maybe this is too obvious, but it had to be said. You can represent vectors by drawing them. In fact, this is very useful conceptually - but maybe not too useful for calculations. When a vector is represented graphically, its magnitude is represented by the length of an arrow and its direction is…
rallain | February 4, 2010Suppose you want to move an empty paper clip box by shooting it with a toy dart gun. Why would you want to do this? Don't worry about that - this is my example and I am sticking with it. Should you shoot a dart that sticks to the box or should you shoot one that bounces off? I made a video of this exact situation. Note: you could obviously come up with other objects to do this with, but I always like to use more normal stuff.
In case it wasn't clear, the first dart bounced back and made the box go much faster (and farther) than the dart that stuck (inside) the box. The usual question is…
rallain | February 3, 2010I am sure I have talked about this stuff before, but it came up recently in a discussion so I figured I should put it here.
Let me draw a picture of learning.
The path of learning goes through the swamp of confusion. Suppose you are in a class and you are confused. This is good. If you are not confused, you are not going through the learning process.
All too often I see a student put their big toe in the swamp. It is icky, so they stop. Their thoughts are:
This can't be the right way. I am sure I made a wrong turn somewhere. I can't possibly go through this. If this IS indeed the way…
rallain | February 2, 2010This one has been on my mind for quite some time. What kind of power source would you need to run a lightsaber? I was actually worried recently about this post when I saw the Discovery Channel show "Sci Fi Science". In that particular episode Michio Kaku talks about how you would actually build a lightsaber. The episode was a little silly, but the science wasn't too bad. In end Michio decides to build a type of hand held plasma torch. Doing this, he estimated that the lightsaber would need a power source on the order of mega-watts.
He didn't do what I was thinking. I am thinking about…