I think I'm finally done with ChargeLab. I made a few fixes and I'm pretty happy with the final result. The new features are:
The number of field lines coming out of charges are now proportional (roughly) to their charge
Fixed the bug where potential was zero at the center of charges. Now it's zero at infinity.
Fixed a bug with termination of field lines. This should speed up field line calculation as well as help prevent field lines from terminating in empty space.
The Field Line Density is higher where the Field Strength is higher.
This is a classic question that I remember seeing when I was a high school student: "How long would it take to fall through a tunnel through the Earth?" My Physics teacher solved the question for us and I'll have to confess only understanding the solution for about 30 minutes. Today I went back and re-worked the question myself. I've presented the solution in two parts.
First, what is it like to fall straight through the earth:
Second, what if the tunnel doesn't go through the Earth's center? What if you want to connect NY to LA for example?
This is a work in progress so stay tuned for updates, but I've been re-working the physics graph templatefor the new requirements in the 2016 Physics Syllabus. The major change is that max and min slope lines now need to consider all data, not just the first and last point.
You can download the updated version here but there are still a few issues (especially when you have data on the negative side of the x-axis). I'll be updating the file soon.
I saw an interesting question posted online. The author wanted to know what the largest triangle that would fit between a graph of y = sin(x) and y = cos(x) would be.
What's the largest triangle that will fit between the blue and green lines?
I haven't been able to come up with an exact solution using geometry or algebra; if you can do it, I'd like to hear how. Instead I made a tool in excel which animates the process of finding an approximation of the solution by exhaustion:
The program searches through all the different triangles to find the largest
I like to mark my student's reports electronically rather than mark paper copies. I type faster than I write and I can copy/paste verbose comments when students do similar things. The major drawback is getting the work back to the students; it's always a painstaking process to manipulate each file into an email or a folder. To reduce that grunt-work I wrote a program that will move files into folders with similar names. I call it Autophile.
The idea is to get your students to put their student ID in the file name so that the software can sort each student's work into their own folder on the network drive. Choose the files you want to sort, select the folders you want to sort them into, adjust settings, and click "Sort"
A confirmation window will pop up telling you where the program thinks each file should go. You can make adjustments or cancel the process. Clicking "Apply Sort" will move the files.
Confirmation Window
The program computes the best match between folder and file by computing something called the Damerau–Levenshtein distance. Basically, it's the number of letters you would have to substitute, remove, insert, or swap to make a portion of the file name look like the folder name.
I was having problems with very short folder names getting picked up as the best match so I modified the result a little bit to favor longer, less accurate matches over shorter accurate matches. I weighted the D-L distance at 100% and the match length at 90% when doing the comparison. For example, I wanted to favor a match that was 5 letters long with one letter wrong over a match that was 3 letters wrong with no errors.
On the 30th of June and 31st of July 2014 I'll be presenting at ConQEST. I'm running two different workshops:
Demystifying Electronics: where we will learn about the basics of electricity, common components, reading circuit diagrams, and common lab tools. We'll get hands-on experience constructing a oscillating circuit on protoboard and measuring its properties
Introduction to Soldering: where we will learn to solder and make a simple Infrared LED light for use with the wiimote whiteboard.
If you'd like to download the notes from either of these workshops they are available here:
Apparently I've been tying my shoes wrong my whole life. Well, maybe not wrong, but certainty sub-optimally.
The problem was that I eschew double-knots because they're too difficult to undo while I found that the standard single-knot had a tendency to come undone in the middle of lessons. I felt trapped between a rock and a hard place trying to choose between interrupting the momentum of the class to tie my shoes or risking it until I have a moment to get the students working independently. I don't mean to overstate the issue but I really felt uneasy about leading a class with untied shoes.
The solution is the double-slip-knot; which is not a double-knot (and that is not a double-negative). It's the right middle ground between the security of the knot and the convenience of pulling to untie. My shoelaces used to come undone about once a day but they have yet to do so once since I've been tying the double-slip-knot.
All of the above links go to "Ian's Shoelace Site," a website dedicated to "Bringing you the fun, fashion & science of shoelaces." I couldn't agree more.
