Ringing A Bridge

Matt and Jared standing on
our experiment

When you strike a bell, it rings at a given frequency.  This frequency is called the resonant frequency and is the natural frequency at which the bell likes to ring.  Just about anything that can shake, rattle, or oscillate will have a resonant frequency.  Things like quartz crystals, wine glasses, and suspension bridges all have a resonant frequency.  The quartz crystals oscillate at frequencies high enough for accurate timekeeping in watches, the wine glasses at audible frequencies to make boring dinners more interesting, and bridges at low enough frequencies that you can feel it when you walk.  It is the resonant frequency of bridges that we decided to measure.

Terminal Velocity 2: A Theorist's Experimental Experiment

Yesterday we rode down Ithaca's hills in an attempt to estimate the terminal velocity of a bike rider braving the city's potholes. But estimations are easy, and we relied on a number of factors - the drag coefficient and area of the bicyclist, in particular - to get them. To see how well we did, it's time to move on to the experimental portion this exercise. Our tools? My bike (figure 1), and my beloved accelerometer (figure 2), with Google's My Tracks app installed.

Figure 1: Our vehicle

Figure 2: Our instrumentation

Teminal Velocity

The impetus for this post lies with three facts. First, I like to bike to work. Second, Cornell sits on a hill. And finally, I'm not very brave.

As a result of all of these, along with Ithaca's less-than-optimal road maintenance, my semi-daily rides home tend to produce a lot of wear on my brakes as I cruise downhill at what appears to me to be very high speeds. I began to ponder just how high this speed really is, and if I could reduce my use of the brakes or if I'm going to end up using them anyway at the bottom of the hill.

The Wrath of Blotto

You may remember when I invited everyone to play my webform version of Colonel Blotto. Well, its still up and has been up for some time, but hasn't seen any action for a while so I thought it might be time to take a look at the results.

Colonel Blotto is an interesting game. It seems to me, that much of this interest derives from the fact that how well your strategy performs is very much a function of which strategies exist in the pool. There is not a clear cut winning strategy, you need to feel out the existing pool and adapt accordingly.

So to stir things up a little bit, in what follows I will share some data from the existing database, refraining myself from commenting too much. Basically, stay tuned for a bunch of pretty pictures which will hopefully get your gears turning. The game is still up, feel free to try to game it now that this information is out. Might be interesting to see what kind of effect releasing the leaderboard will have on the leaderboard.

Steak Dinner

Sorry about the blog hiatus. During the summer, without teaching classes, inspiration is harder to come by. But, tonight I cooked a steak. I recently got a new digital meat thermometer. My plan was to slowly cook the steak until the internal temperature got to be about 140 degrees Fahrenheit with the oven at 200 degrees, take it out, wrap in tin foil, crank the oven to 500 degrees, stick it back in, and give it a nice exterior, reaching an internal temperature of about 150 degrees which would put it at about medium.

After I put the steak into the oven though, I started to watch the temperature go up on my digital thermometer and thought, why not take data. And so I did. Here are the results.

Above you see the internal temperature of the steak as a function of time. First some comments about the graph.

On the Death of Karl Schwarzschild

Every once in a while, in the study of science, one comes across biographical snippets that momentarily breathe life into names that otherwise serve as shorthand for equations and eras.  As an obvious effect of the selection bias involved with including this superfluous information in technical books, they are bound to be pretty interesting.  Such stories range from the hilarious antics of Feynman [1] or Fermi [2], to the heartbreaking stories of Boltzmann and Oppenheimer, and even to the surprisingly scandalous life of Erwin Schrödinger.  But my all time favorite of all these historical "fun facts" is that of the man who provided the first exact solution to the Einstein field equations while fighting in the First World War:  Karl Schwarzschild (pictured left impersonating a surprised walrus [3]).

Something Bugging Me

Apparently July is a quiet month here at the Virtuosi.  We're busy with research, travel, vacation, etc.  I, myself, have been busy with only a few of those things, though I've also been studying for my qualifying exam, which is coming up in less than a month.  However, that's not the question before us today.  Today I'd like to think about the density of bugs in the air.  I was walking outside this past weekend, there was a fierce wind blowing, and twice in five minutes a bug hit my ear.  That seemed like a lot.  But for 1 hour of previous walking no bugs hit my ear.  How many bugs would there have to be per cubic meter of air to achieve that rate?

Zombpocalypse

Here at the Virtuosi, we're concerned. We are concerned that perhaps the world is really not ready for a zombie apocalypse. You know, the kind of zombie apocalypse that you may have seen in such classics as "Night of the Living Dead", "Shaun of the Dead", or perhaps the even more recent "Zombieland" (sweet cameo by the way). The kind of zombpocalypse that could leave major cities void of life and the country plagued with the undead.

Well, Alemi and I were curious as to how likely such a pandemic was to occur and what it would look like in the simplest of models. In typical Virtuosi fashion, we threw some physics at it and this is what we came up with.

The Impossibility of Why

So I think we've all been rather busy here.  Hence the lack of posts.  I'm going to try to keep this one short but sweet.  A lot of people think that physics tells us why things happen.  Why is the sky blue?  Why does the earth orbit the sun?  Why does copper transmit electricity so well?  These all seem like perfectly reasonable questions to ask.  Questions that we, as physicists can answer.  Yet, I entitled this post the impossibility of why.

In general, questions about why are not good questions for physicists   More accurately we answer questions about how.  Or what.  What phenomena causes use to see the sky as blue?  What forces cause the earth to orbit the sun?  How does copper transmit electricity so well?  In general, we can't answer a question of why.

Life as an Experimenter - Reflections

I've been doing experimental physics for about three years.  I started during my sophomore year in college, went straight to graduate school, and continued here (albeit not quite immediately).  There are people out there who have been doing this for a lot longer than I have, but I've gained a few insights, by working with said people, and through my own experiences in the lab.  I thought I'd try to share a few of these, to help illuminate the past few days I blogged about.