Maybe you have already seen an announcement, or maybe this is the first time you heard that wired.com is starting a new science blogs section. Oh yeah, and they invited me to join. So, I did. This brings a couple of important notes. First, this will obviously be my last post at scienceblogs.com. You might want to change your blogroll and rss reader to the new address: http://www.wired.com/wiredscience/dotphysics And RSS feed at http://www.wired.com/wiredscience/category/dot-physics/feed Note that other than the address and different banner, everything will pretty much be the same. Second,…
Here is the next item. There is a threaded plug on the top. I took it off so you could see inside. The whole thing is pretty heavy. Good luck, and let's be careful out there.
Through random surfing, I found this clip from The Amazing Race (which is apparently some type of reality show). Don't really know the set up except that it appears some girl is trying to launch watermelons with a slingshot. This looks bad, but she seems to not be seriously injured. Watermelon smashed on face. Wow. What can I we calculate here? Bring in the video analysis. How fast was the watermelon going? First, this is not a very good quality video. The frame rate sucks and there is a very slight panning and zooming (which I will ignore) Second, I really don't have anything to scale…
Actually, it should be called Happy "Magnitude of the local Earth gravitational field" day. You know, 9.8 N/kg on September 8 (9/8). Get it? Well, the idea was for the physics students and faculty to build some stuff to do outside - projectile motion type stuff. Well, we had the idea a while ago and then kind of forgot about it. In order to just get something done, I set up the "shoot the falling target" demo. (previously known as shoot the monkey). Here is a quick video demo (seriously - first take too). What is going on here and what does this have to do with g? Well, it doesn't…
Congratulations Fran. Not only did she answer the "What the heck is this?" correctly, she was the first commenter. Here is the original item: It is of course a gas discharge tube. You put these tubes in there (as shown above) with helium or neon or whatever in there and it excites the gas to give off light. Honestly, we have like 10 of these things laying around. Some of them are newer and say "Danger 5000 volts"), but these older ones say nothing. Here is an example of one of the first ones I saw. I didn't figure out what it was for a while because most of the ones we have don't have…
You can call it football if it makes you happy. Anyway, this is a popular story going around. The physics of the magic curving soccer kick. Here are two ends of the spectrum. First, there is the lower, easier to consume version from io9.com Physics forced to come up with whole new equation to explain "impossible" soccer kick I will summarize this article for you: "Have you seen these crazy soccer kicks where the ball curves? It happens because the ball spins and physics. Here is a video" Oh, and they have a diagram - which doesn't seem to come from the original paper and they also have…
Please note the official change of the title of this game, it is no longer "what is this". Here is the item: I suspect someone will know what this is. Honestly, I didn't figure it out right away. However, I have found that the readers as a group generally are more knowledgeable than me by myself. Oh, I don't think there is really much description to add here. I included a meter stick for scale. P.S. How come a device for measuring temperature is a thermometer and a device for measuring electric potential is a voltmeter? Shouldn't the meterstick be called either a length-meter or a meter…
Yes, I love python. However, I am no expert. Most of the stuff I write in python is dirty and ugly code. Sometimes I figure out new things (things that programmers already know) and sometimes I forget these things. So, here are a few tips and tricks that I use from time to time. Really, I am writing this for future Rhett when he does a google search for "how do you save data to a file in python". Saving data to a file Suppose I am modeling a basketball falling through the air. I want to plot this data, so I save position and time data in lists. For example: Here is the info from scipy…
A while ago, we had a ton of lightning. As a bonus, it always happened in the middle of the night. I love sleeping where it sounds like I am on the front line in WWI - no, I don't. But, while lying awake waiting for the next BOOM I thought of something. Instead of just counting the time between flash and boom, maybe I could make a lightning detector. For mere mortals, the first step might be to google "lightning detector". I don't want to do that. What fun would that be? I did look up something. The current in a typical lightning strike is on the order of 30,000 amps. How could I…
The first thing that I saw was this article from nola.com (The Times-Picayune) "New teacher evaluation method being proposed in Jefferson Parish". Let me summarize this article. Basically, one of the local School Board wants to use a learning tool (Interval Testing) as a teacher evaluation tool. The Interval Testing program gives students spaced out evaluations through out the year to help them (and teachers) assess the preparedness of the students. These are non graded assessments and have been shown to help students. Note - the purpose of the implementation of Interval Testing is to…
This is something I use at the beginning of a semester. I ask the class: "How are you an expert?" What is an expert? Let me call an expert someone that is comfortable answering questions about that particular topic. If students are too shy to share (especially on the first day of class), I will start it off. I am an expert in: Some (but clearly not all) physics stuff. In particular, classical mechanics, physics education, numerical modeling (though not really an expert - but I could answer questions). I can play the clarinet and saxophone - but I haven't practiced in a long while I…
Reader Fruity was the first to correctly name this device - on just the 9th comment. Impressive. Honestly, when I found this thing I had no clue. I asked other physicists and none of us were sure. However, I did find the answer. Let me show you my secret. I don't know how old this thing is, but it is old. When I open it, my nose and eyes get all tingly - probably from the mold. Here is that apparatus in the book (tome): I can't show you the whole page because it has other stuff of awesomeness that I want to show you later. But, I can show you the description for that item. I am…
Ghostbusters is old enough that I don't mind giving away some spoilers. If you haven't seen it, I doubt you are going to. In the movie, the Ghostbusters capture some ghosts. They keep these ghosts in some "containment grid" device. Someone from the city doesn't like this and comes to turn it off. After much searching, I found the clip. I am going to talk about Louisiana education and tenure, but first I will look the players in the above scene. What were they thinking? Here is my guess. Walter Peck: These Ghostbusters are a bunch of frauds. They are just stealing money from people…
It would be nice if I could come up with a good rhyme for grade to fit this title. One of my brothers is a biochemistry faculty at Appalachian State University (hint - he is the one with the same last name that I have). We were talking (and surprisingly agreeing) that grades were dumb. What would happen if we stopped grading? Wouldn't that be awesome? So, what would happen if there were no grades? Here are some thoughts. We would only have one job in the class - help students learn. The second job of evaluating student understanding would only be there to help them learn more. It would…
Here is my plan. Post a "what is this" on every Friday until I run out of things. I will post the answer on Tuesday. Maybe we should start keeping points. You get more points for being the first one to get it right. You lose points for getting it wrong. Last week was easy, but I think this is more of an appropriate level. Here it is: Nice - it has a tag, but no part number. Honestly, this one stumped me for a while. If you have any reasonable questions, I might answer them.
Might as well jump. Jump. Go ahead, jump. - Van Halen Suppose everyone in the world got together and jumped. Would the Earth move? Yes. Would it be noticeable? Time for a calculation. Note: I am almost certain that I have done this before, but I can't find where. Starting assumptions. 7 billion people. Average weight: 50 kg (you know, kids and stuff) Average vertical jump (center of mass): 0.3 meters - and I think that is generous. Mass of the Earth: 6 x 1024 kg Gravitational field near the surface of the Earth is constant with a magnitude of 9.8 N/kg Ignore the interaction with the…
You know I wander around the intertubes, right? Who doesn't? Anyway, I saw this collection of strange google Earth images. Yeah, it is kind of dumb, but this one made me think: That article said the image was from TechEBlog, so there is that. I have no idea what this thing is, but it is clearly tall. How tall? Instead of searching online for info about this structure (that wouldn't be any fun), I figured I could do a quick analysis of the shadow. Here we go. First, I need to make some measurements. It turns out that Tracker Video tool for analysis is also quite excellent to use for…
Austria seems like a nice place to visit - I have never been there. However, I am not going to Salzburg (even though I said I was). The original plan was for WOMWorld/Noika to fly me to visit Felix and the Red Bull Stratos team. It was an exciting plan. Now there is a new plan. The new plan is for me to instead go to the ACTUAL Red Bull Stratos Jump. I know it is not Salzburg, but in my mind this is a huge upgrade. Ok, I can't help it. This is the first thing that came to my mind. Me: But I thought I was going to Austria. We had a deal. WOMWorld/Nokia: I am altering the deal. Pray I…
I might as well make a new tag called "basketball throws" because I can't stop with the analysis of these crazy basketball shots. Watch - in the end someone is going to post a video about how all these were faked (and I have said there is no clear evidence they are fake). Oh, if you want to see some shots that I am talking about - just search for Dude Perfect on youtube. Physically, these crazy shots are possible. Time of flight in the video is comparable to a numerical model. But, the question is: how difficult are these shots? Are these one in a million? Are they easy? Are they…
Perhaps you have had enough time to think about the first "What is this" demo item. Here is the item in question. It seems most of you were right on track with this one - probably because you can still buy such a device. This thingy launches a small ball horizontally while at the same time dropping a ball. It is supposed to show that the vertical and horizontal components of an object in projectile motion are independent. It takes two balls (which I didn't have when I took the picture). One ball goes on each end and the arm is pulled back. Update: Thanks to Kevin and Frank for pointing…