Rhett Allain
rallain
Posts by this author
April 13, 2009
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…
April 12, 2009
I already talked about increasing the temperature of a pool. My father commented that he thought the pool level rose by like half an inch when the temperature increased (by about 10 degrees F). So, this leaves the question: Is my father crazy, or is this possible? Or are both true?
Does water…
April 11, 2009
It is spring break, so we are at my parents house for a couple of days. The kids like it because there is a pool, a heated pool even. It really isn't that cold outside, but yesterday the water measured at 62 oF. So, with some help from the kids, we cleaned out the pool and turned on the heater…
April 10, 2009
I am so pumped up that MythBusters is back on. Not only do I like the show, but it offers so many blogging opportunities. Their latest show featured car crashing myths. One of the myths from the episode was a redo of the myth where two trucks crash head on simultaneously crushing a smaller car…
April 9, 2009
This post has nothing to do with physics, so if you are only into physicsy stuff, skip this. The primary goal of this post is to list what I need to blog. The secondary goal is to rant about my laptop.
I destroyed my laptop (well, not really, but kind of). Basically, I had a tooth pulled on…
April 7, 2009
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…
April 7, 2009
Dan Meyer at dy/dan just posted about teacher-student analogies. His analogy is that the student is like a weight lifter and the teacher is the spotter. I like this. It is similar to my usual analogy that the teacher is like a trainer and the student doing some exercise. Another analogy I often…
April 6, 2009
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…
April 3, 2009
I found this video to be very entertaining.
Dry Ice is LEEEEEEATHALLY DAAAANGEROUS? - These bloopers are hilarious
William Beaty's site has tons of great stuff - http://www.amasci.com/
March 31, 2009
What is a fake force? A fake force is one of those forces that introductory texts tell you aren't real - like centrifugal force. They aren't real in the sense that they are due to one of the fundamental interactions. Basically, introductory texts (and even blogs like this one - not a bad summary…
March 25, 2009
Tom and Jerry, or Fetch! with Ruff Ruffman?
Answer: Tom and Jerry.
What? Yes. The reason: Tom and Jerry has bad physics but does not pretend like it has good physics. I know this is probably going to "type-cast" me as "that guy that keeps attacking Ruff Ruffman." Soon to be followed by "Leave…
March 25, 2009
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…
March 24, 2009
There are some really cool questions out there. Questions that do not require a lot to ask and do not require a lot to answer. Here is one such question (I can't remember where I first found this question or something like it):
Suppose you put take two identical cans of soda out of the fridge and…
March 23, 2009
I have always wanted to ask a question like this - but never found the right test for it. Perfect for a blog.
Question:
Suppose you are in your car at a stop light behind a truck. The truck is pulling a trailer with a rollable tractor on it.
When the light turns green, the truck starts to…
March 20, 2009
So, I was in the student computer lab helping a student with a numerical calculation. I couldn't help notice the student next to me was registering for classes. Here is here strategy:
Look at required courses.
Check available classes.
Check ratemyprofessor.com.
Re-check available classes.
Repeat…
March 19, 2009
I just got back from judging elementary level science fair (this is like kids in 6th grade or something). Here are some quick notes in no particular order.
Please, please do not have a 20 item list of supplies that you used on your board including things like thumb tacks, tape, paper and poster…
March 17, 2009
Dear Ruff Ruffman,
My kids really like your show. However, there is a problem. You promote it like it is science, but the content keeps having mistakes in it. Previously, I pointed out your mistake about in infrared thermometer (if can't remember, you said the thermometer measures the…
March 16, 2009
Better technology sometimes causes problems. In this case, technology has made video cameras really small. Small? That's a problem? Well, the problem (as I discussed previously) is that small cameras are not stable and make "shaky" videos. Well, then increase the mass of the camera - simple.…
March 16, 2009
I previously talked about measurements (some) when I looked at the uncertainty in the distance to the Sun. One of the simple ways of determining the uncertainty of a calculated quantity is to use the uncertainty of the measured variables and find the max and min that calculated quantity can be.…
March 14, 2009
I don't know if you noticed, but this blog has been down almost a week. Several things happened. First, I was hosted by Lunarpages. That didn't go so well. They ARE cheap, but maybe that is for a reason. I won't really go into details except to say that they have CPU limits, but you can't…
March 6, 2009
Temperature is a pretty weird thing if you think about it. How do you best define temperature? Let me go ahead and give you my favorite definition:
Temperature is the thing that two objects have in common when they have been in contact for a long time.
Yes, that is a good definition. Maybe now…
March 4, 2009
Some time ago, I wrote about the awesome things the Greeks did in astronomy. Basically they calculated the size of the Earth, distance and size of the moon and distance and size of the sun. The value obtained for the distance to the sun was a bit off, but still a bang up job if you ask me. (where…
February 28, 2009
This idea comes from my friend Thomas. His son is like mine in that they both think LEGO are awesome, and they are correct. For some reason, Thomas decided to calculate the price per piece of LEGO in each set. To promote repeatability, I decided to do this also. Looking at the catalog at LEGO.…
February 26, 2009
First, I think we should all be using smaller lighter cars. They get better gas mileage, they are better for the environment and maybe even reduce traffic? (ok, not sure about that last one - but it is possible). In Buzz Out Loud 918, they were discussing Toyota working on new car bodies built…
February 25, 2009
I overheard this high school student complaining about a teacher. Here is essentially what she said (about a class her friend is in):
"This teacher is crazy. He said we have a test the next day and he gave them a study guide. But he didn't give the answers to the study guide. My friend and her…
February 24, 2009
Basically, the title says it all. Here is a short tutorial on projectile motion calculations with a spreadsheet.
Record your screencast online
I left out a lot of details, so maybe these links will help:
Spreadsheet tutorial for numerical calculations (video)
More details on numerical calculations…
February 24, 2009
Quantum mechanics is not my area of expertise. Really, I have no area of expertise. However, I think it is time to bring the whole photon thing back up. Yes, I know I was a little harsh before. Maybe I should start over.
First, models. Yes models. I think science is all about models.…
February 21, 2009
This is one of my favorite demos. Easy to do and doesn't really require any equipment. The basic idea is that you support a meter stick horizontally with two fingers. Slide your fingers in and they will both meet at the center of mass. Here is a video.
Meterstick friction demo from Rhett Allain…
February 19, 2009
After talking about textbooks, commenter Kevin posed the question: which would cost more, printing out a free book or reusing a purchased textbook. Great question. How about some quick estimation (some of this stuff I have no clue about). First, how much do high school textbooks cost? Probably…
February 19, 2009
I saw this some time ago, probably in The Teaching Professor online magazine thingy. The basic idea is to leave your class alone when they are having a discussion. I have done this a couple of times. Yesterday was the first time this semester. Here is the deal. In this class (Physics for…