Rhett Allain
rallain
Posts by this author
March 10, 2010
Pi day is March 14th - get it? (3.14) I am a big fan of Pi. Here is my first post to celebrate the awesomeness of Pi (I know this is early, but I was too excited to wait).
How can you determine Pi?
Oh sure, tons of high schools do the classic experiment. Measure the circumference and diameter…
March 8, 2010
I know many readers like the fermi questions (like how much would it cost to review all youtube submissions). Well, you are in luck - Diary of Numbers is having an estimation contest. Here is the question:
Mario has appeared in over 200 video games as Nintendo's main mascot. He has starred in TV…
March 8, 2010
Hat tip to Frank for sending me a link to this video:
If you have never done a demo like this (without the motorcycle), you should. It really isn't too difficult. Here is a video of my version:
Inertial demo from Rhett Allain on Vimeo.
So, the question is: is the motorcycle thing real or fake?…
March 4, 2010
Check out this thing.
That is where the guy (Jem Stansfield of BBC's Bang Goes the Theory) shows how he built this thing. Here is part 2 where he uses it to climb a building.
Here are some questions:
Why does it not matter how powerful the vacuum is?
How does a vacuum cleaner work anyway?
How does…
March 2, 2010
Perhaps an alternate title could be "hey, lets have class outside." I think I understand why students say this, but my standard answer is "no". Oh, but there is XYZ that we need to do. Here is the point I am trying to make - class is for students. Class is not for me. Students pay for classes…
March 2, 2010
Note: The following is a repost from some time ago. Today is the officially day to celebrate Dr. Seuss, so here is my Seuss-related post. Enjoy.
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…
March 1, 2010
There was a Buzz Out Loud episode in the not-to-distant past where the discussion of youtube came up. I can't remember the exact details, but the main point was that it would be impossible for google (the owners of youtube) to review all of the videos that were submitted.
And here is my…
February 28, 2010
I ride my bike and mostly the wind makes me unhappy. On a very few days the wind is with me on the way to work and then changes so that it is with me again. But most days the wind is fairly constant. So, if the wind is constant then shouldn't everything even out? (Even Stephen).
Assumptions:
Let…
February 25, 2010
I thought this was an interesting idea. One of my colleagues does not collect homework. Instead, the students turn in a sheet that lists which homework problems they worked on and how much time they spent on homework. By doing this, the students get a small homework grade - independent of how…
February 23, 2010
I had so much fun creating graphs for the Red Bull Stratos Space Jump calculation, that I figured I should make some more.
Can you fall faster than terminal velocity? That is the question.
Air Resistance
Air resistance is a force exerted on an object as it moves through some stuff - air in this…
February 22, 2010
My 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…
February 20, 2010
The 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…
February 19, 2010
Red 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…
February 17, 2010
It 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…
February 16, 2010
Do 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…
February 16, 2010
Now 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)…
February 14, 2010
I 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…
February 13, 2010
Do 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…
February 11, 2010
Do 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…
February 9, 2010
Forgive 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…
February 9, 2010
Note: 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…
February 8, 2010
This 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…
February 7, 2010
I 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…
February 7, 2010
Looks 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…
February 6, 2010
So, 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…
February 5, 2010
The 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…
February 4, 2010
Recently, 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…
February 4, 2010
Suppose 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…
February 3, 2010
I 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…
February 2, 2010
This 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…