What Keeps a Train on the Track?

At first, it may seem very simply and obvious: the flange keeps the wheel on the track, right?

Nope, that’s not the answer!

To understand why, let’s first get some background on how train wheels are made:


The primary take away from the above video is that train wheels are big and come together with a joined axle — that is, they don’t have a differential. If you don’t know what a differential is, or want to be impressed by an awesome video from 1937, take a look-see as this:

That still doesn’t explain what keeps a train on the track though. If you haven’t been able to figure it out yet, Feynman will explain:

…and that’s called rail adhesion.

via Kottke


Seattle has an Accent

I was playing catch-up with my RSS feeds when I stumbled upon this little gem from kottke: 21 accents in 2 minutes 30 seconds.

The women, Amy Walker, pretty much does exactly what the title would suggest: 21 accents in 2 minutes 30 seconds. No surprise there. Skip forward (or just wait, because the rest of her accents are actually pretty good) to 1:45 and you’ll get the Seattle accent.

Now, up until this time, I was never aware that Seattle had it’s own distinct accent. As it turns out, Seattle may. I found a 2005 article by the Seattle PI (that would be “Post-Intelligencer” for all you non-natives), Contrary to belief, local linguists say Northwest has distinctive dialect, that reports that “Jennifer Ingle, a 27-year-old Ballard native and student of language at the University of Washington” did a study on the Northwests’ distinct accent:

From seattlepi.nwsource.com:

Say “caught” and “cot” out loud. If you’re a true Northwest speaker, the words will sound identical. Linguists call this the “low-back merger” because we’ve merged these two vowel sounds. On much of the East Coast, these same words will sound different. “Creaking is a way of making those distinctions that are being lost,” Wassink said. Just as Bostonians tend to compensate in their speech for removing the “r” from many words, she said, we might speak creaky to compensate for refusing to use both vowels.


Turning Spheres Inside Out

Have you ever wanted to turn a sphere inside out? How about without creases or sharp corners? Warning: Math content to follow!

The following 20 minute video will show you how:

via kottke