video analysis

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 the field on the surface of the Earth. This means that the acceleration of a free falling on the object would be 1/6th the acceleration on Earth. So the question is: how would you change the time scale of a movie so that it looks like its acceleration is 1/6th of 9.8 m/s2? *If you make the size of…
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 already seen it anyway). Basically, Hancock gets upset with this boy and throws him in the air to scare him or something. In case you did not time it, the kid was in the air for 23 seconds. I claim that in order for Hancock to throw a person in the air for this long, the acceleration during…
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 Howitzer cart). The video is available at the LivePhoto Physics site. Screencasts and videos online
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. Anyway, here is the part I was curious about. Did the exploding hammer lift him off the ground, or did he jump as a reaction to the explosion. It kind of looks like he was lifted, but I am not sure that is possible. Video analysis to the rescue. (using Tracker Video) So, I assumed the sledge hammer…
I haven't seen the Pixar Movie "Up" yet, so don't spoil it for me. I have, however, seen the trailer. In my usual fashion, I have to find something to complain about. There is this scene where the old man releases balloons out of the house. What is wrong with this scene? Also, would that be enough balloons to make the house float? Here is a shot of the balloons coming out of the house. Ok, I was already wrong. The first time I saw this trailer I thought the balloons were stored in his house. After re-watching in slow motion, it seems the balloons were maybe in the back yard held down…
I think the Mythbusters have a wonderful opportunity for educational outreach. Take this week's episode. One myth was to see if arrows fired from a moving horse penetrated more than arrows fired from a standing position. They first did this with real horses, but they said the data was not convincing. I am pretty sure they had more than 10 trials recorded (there was a glimpse of the notebook). I would love to see this data and find (or let students find) the standard error of these measurements. This would be a great exercise to see how this whole uncertainty thing works. As long as I am…
Last night was Wednesday, so of course I watched Mythbusters. You never know when a good blogging opportunity will come up. I could talk about the kinetic energy of arrows, but instead let me talk about their episode for next week. I only caught a glimpse of it in the preview. It looks like they are doing something about jumping on a see-saw and launching the other person. It could be this video they are looking at: EMBED-Extreme Catapulting - Watch more free videos From my analysis of this video, I found that the likely outcome was a broken board (if it were not fake). Also, if the…
In the second Cat in the Hat book (I think it is the second one), the Cat reveals that he has more smaller cats under his hat. They are labeled A - Z with Z being so small you can't even see. Question: What is the sequence of sizes for successive cats? How big would Cat Z be? Here is the first picture that Cat reveals Cat A. It is not trivial to measure their relative sizes because they are in different positions. I drew two circles, one around each head and looked at the circle sizes. So, Cat has a head that is 165 px tall and Cat A has a head 61 px tall. Let me call the total length…
Previously, I showed how to analyze a cat video with Logger Pro. Logger Pro is nice, but so is Tracker Video. I also posted a comparison between Tracker and Logger Pro. Now, here is the same tutorial on the same video using Tracker Video. Record your screencast online I am not going to go through the analysis, since it would be the same as with Logger Pro.
I recently posted a tutorial on using Logger Pro for video analysis. Why did I use Logger Pro? Why not Tracker Video? Here is a quick comparison of the two. Logger Pro In the previous tutorial, I used Logger Pro. The primary reason was that the tutorial was for a lab course. The students were already familiar with Logger Pro. Here are some of the pros of Logger Pro. Fairly straight forward to use. Good graphing and curve fitting utilities built in. Integration with data from other sources. If you video a ball falling and also use a motion detector, you can "sync" the data. Not really a…
Cats can be entertaining - especially when they are someone else's cat and that someone made a video. Really, this post is about analyzing video with Logger Pro (in a tutorial type fashion). I just happens that I chose this cat video to analyze. Here is the video: I am going to look at the part where the cat gets on the fan. I will try to step through the analysis so you can do your own. Get the video Actually, the first step is to find a video. YouTube has tons of stuff. Also, you could make your own video with a camera. A couple of things to make your life easier: A non-zoom video.…
Dan Meyer made this awesome photo. He posted it so that others could look at it and come up with lesson ideas to use with this. There are some very good suggestions in his comments. I wasn't going to analyze this because I didn't want to rob some students of the opportunity, but I can't resist. Also, I doubt the first step a student would use would be to google for the answer. HA! I just caught you, you googling student. Ok - I will try not to post any data. However, I will post some info on how I analyzed this. The photo is a composite image from a video clip of a person throwing a…
I enjoyed the super bowl commercials for the most part. You have to be careful not to have too high of expectations, or you will set yourself up for a big letdown. Here is a quick analysis of one of the commercials. This is a Bud Light commercial where at the end they throw a guy out of an office window because he suggests they save money by not buying beer. Are there any actual office meetings that serve beer? (Sorry if I spoiled the ending for you) I am going to analyze the motion of the guy going out the window. Just because. At some point in the future, I am going to make a short…
We have all seen the Kobe Bryant video of him jumping over an Aston Martin - this keeps coming up on the Internet. There has been vast discussions of whether this is real or fake. I will do my best to examine the evidence. In short (in case you don't want to read the whole thing) Kobe can most likely really jump that high, it is possible that there was some perspective trickery involved. Here is the video in case you are brand new to the WWW: Oh - don't forget I already analyzed Kobe Bryant jumping over a pool of snakes. I voted that was real. First, let me give a personal note to Kobe and…
When you pour a beer, there is this foamy top called the head. The size of the head decreases over time. What is this process dependent on? Clearly, little bubbles of beer are popping. Does each bubble have an equal probability of popping? Do only the bubbles on the top (or bottom) pop? I became aware of this idea from a colleague. Maybe he was going to do an analysis, but I haven't seen it yet. If you do (Gerard), I am sorry for doing this before you. This may have been investigated before, but in the spirit of re-doing everything I have not searched for previous beer head studies.…
So, here is a video (from break.com - so you know it is likely fake). null - Watch more free videos If for some reason, you can not view this video, here is the plot. Guy wears parachute and brings a portable thing like a see-saw. Guy approaches large crane dropping a large mass repeatedly (I assume to flatten a dirt road) Guy sneaks up an puts the see-saw under the area that the mass drops on and then stands on the other end of the see-saw. Mass drops, guy shoots up and parachutes down. So, why is it fake? I think the best thing is to give an analysis of the see-saw. To start this analysis…
I saw this video posted on Physics and Physicists: It reminded me that I had at one point tried to analyze this. I had actually posted something about this on the first generation of my blog (which no longer exists). I have found the analysis, and here it is from the archives. Thanks ZZ for reminding me. Could this be true, or is it fake? I started to do an analysis of the trajectory, but I found the following frames: Look at the guy's back. His back starts moving before the water bottle rockets. It must be some type of cable pulling him. If the rockets were propelling him, the rockets…
Clearly, I am not a professional blogger. I am an amateur. This is because I was under the impression that only amateur bloggers could compete in the blogging olympics. When did they change these rules? Anyway, Adam Weiner did a physics-based analysis of the latest Star Trek movie trailer. Here is the trailer: In the trailer (oh, spoiler alert) a young Kirk jumps out of a car before it goes over a cliff. It does look odd, and that is why I had intended to analyze it. In Adam's analysis, at PopSci.com the basic approach was: Take the initial velocity of the car (from the clip) Assume the…
Ok - I like Alabama football (sorry, but it's true). There is a clip on youtube of the end of the Alabama-Auburn game where the fans sing the traditional "Rammer Jammer". If you don't know what that is, don't worry. I am not sure I completely approve of the cheer, but it is a tradition. If you are curious, here it is: So, what is cool about this? Notice that the entire crowd is yelling the same thing, but they are out of sync. Can this be used to estimate the size of the stadium? I made an audio file from that youtube clip and looked at it with Audacity. Although I am completely…
This is an old video, but still interesting. In this video clip, Kobe Bryant jumps over a pool of snakes. You are probably thinking what I thought when I see that - this doesn't look real. Really, it must be fake. Why would Kobe jump over a pool of snakes? Isn't that dangerous (even if there were no snakes in there he could hurt himself). Video analysis is needed. Is this fake or is it real? Start with my favorite video analysis tool (tracker). Use this to get position time data. Step 1: Get the movie. I used Mpeg Streamclip to get the movie in quicktime format from the flash video…