Dr. Matthew Weathers is an assistant professor of Mathematics and Computer Science at Biola University and also a world-class showman. Here are some of his biggest hits (often for Halloween or April Fools’ Day). Enjoy. (If you’re interested, you can find more at his YouTube page, http://www.youtube.com/user/MDWeathers/videos?sort=p&view=0&flow=grid.
Category: Technology
Measuring terminal velocity
Using a simultaneously falling softball as a stopwatch, the terminal velocity of a whiffle ball can be obtained to surprisingly high accuracy with only common household equipment. In the January 2013 issue of College Mathematics Monthly, we describe an classroom activity that engages students in this apparently daunting task that nevertheless is tractable, using a simple model and mathematical techniques at their disposal.
The Hitchhiker’s Guide to the Galaxy
In 1979, Douglas Adams envisioned the iPad at a time when the Apple II was the state of the art. From now on, I’ll always think someone’s reading the Hitchhiker’s Guide to the Galaxy when they’re fiddling with their tablet (especially if they also have a towel nearby).
“[Ford Prefect] also had a device that looked rather like a largish electronic calculator. This had about a hundred tiny flat press buttons and a screen about four inches square on which any one of a million pages could be summoned at a moment’s notice. It looked insanely complicated, and this was one of the reasons why the snug plastic cover it fitted into had the words DON’T PANIC printed on it in large friendly letters. The other reason was that this device was in fact that most remarkable of all books ever to come out of the great publishing corporations of Ursa Minor — The Hitchhiker’s Guide to the Galaxy. The reason why it was published in the form of a micro sub meson electronic component is that if it were published in normal book form, an interstellar hitchhiker would require several inconveniently large buildings to carry it around in.”
From Chapter 3 of “The Hitchhiker’s Guide to the Galaxy.”
Bug in TI-83 Plus?
On my TI-83 plus emulator, I input the following in the statistical command 2-SampTInt:
x1 = 51.71
s1 = 0.79
n1 = 10
x2 = 136.14
s2 = 3.59
n2 = 10
C-Level: .95
Pooled: No
The calculator returns 9.896 degrees of freedom; it should be more like 12 degrees of freedom according to Welch’s formula (which is also implemented with T.TEST in Microsoft Excel).
I’m assuming the TI has some non-standard way of computing the number of degrees of freedom, but I haven’t the faintest idea what it could be. What’s odd is that the number of degrees of freedom appears to be computed with Welch’s formula when using the parallel command 2-SampTTest.