HW 4, revised due date

The remaining HW4 problems were originally planned to be due on Friday 7 March. However, I think this week we spent (arguably) too much time on the rocket launchers and not enough time on problems. As a result, I suspect that the problems you have left may seem a bit too difficult to finish by Friday.

Therefore, I'll postpone the due date of the remaining (non-daily) problems until Monday 10 March, and I'll plan to go over the HW problems in Friday's class to get you started.

Also, as it turns out, XKCD has pointed you toward one of the solutions already. The author has a degree in physics, so this is the rare case where you can actually trust a webcomic to help you with your physics homework. (Seriously, read XKCD.com and what-if.xkcd.com, they are a valuable use of your time.)

Rocket Contest

Well, I was pleased, and had a good time :-) I thought it went well, and you all did a great job. The visitors were pretty impressed with what you were able to come up with, and in particular the variety of solutions presented.

By the way: no one will come out of this with a bad lab grade, I was impressed all around. Even if you didn't get as many 'hits' as you would have liked, it was clear you all had solid approaches and took the task seriously, and that's worth a lot.

Currently, I'm uploading many photos and some video from today, but I'm not quite finished yet ... I'll post some links here when it is finished. Keep your eyes on the Tuscaloosa news, they may run a story based on the video and pics they took today.

Also: I've decided you can keep the launchers, sensors, and laser pointers - your lab fees more than paid for them, and at this point you put a lot of work into the customizations. I do need the voltmeters back if you still have them though ...

In the mean time: here is (1) a UA news bit, (2) a short video of a successful shot, thanks to Marcy Huey's fine camera work, and (3) a listing of several other videos, including team Red Scare's propaganda.

(All videos are AVI straight from my camera; editing and conversion to mpeg should happen this weekend I hope.)

Physics Majors event

Just FYI, since a number of you are physics majors ...

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All PHYSICS MAJORS!!!

Do you actually know other physics majors?? Yeah, that's what I thought. So come to the meet AND greet.

FREE FOOD! Yes, completely free. In fact, it will even be surrounded by nerds. So come.

DETAILS:
Who - YOU....hopefully...
What - Meet the other people who share your uniquely awesome interests
When - FRIDAY, as in THIS FRIDAY of dead week. which is May 1st, just fyi. 3:00-5:00pm
Where - Room 109 in Gallalee (obviously)
Why - because Tara and Ted were upset that we didn't know all of you

So, it'll be awesome, especially once you get there :)

-Your Fellow Physics Majors, Tara and Ted - and kind of the Society of Physics Students, kinda -

Standing waves in your shower

Important application of waves.

Today's bit of randomness

Physics is good for anything. Anything.

Following twitter updates, if you're in to that sort of thing

I am putting out some homework hints via twitter now, just as an experiment. You do not need a twitter account to follow these updates.

(1) the twitter updates will also be mirrored as my facebook status. You can look at my wall on facebook and see the same stuff.

(2) go to http://twitter.com/pleclair periodically

(3) get an RSS feed of my twitter updates, then you can read them in your aggregator of choice. You can get a facebook application to bring RSS feeds to your facebook homepage, fyi.

(4) (update:) follow the little twitter-box on the right side of this page ... type "pleclair ph125" in the box and hit "set."

One obvious question is why bother with this. I don't know, actually - it may not be worth the trouble. My thoughts:

(a) it is easy to follow twitter updates on a mobile device (if you have enough text messages in your plan). this means you can get HW hints and stuff without having to be near a computer.

(b) it takes me like 5 seconds to make a twitter post, whereas even on the blog I tend to spend 5-10min or so composing a post. If it is easier for me, I am likely to do it more often (even under savage time pressure), and the more help you get. (The reason I switched to a course blog in the first place was speed & frequency over static web pages.)

(c) On the other hand, having this blog is probably plenty already. I may be overthinking this problem, or going toward too many channels of information.

Theory

This loosely sums up how I feel about theory & calculations. At the end of the day, someone still has to go and look. A reality check, if nothing else.

Also, it is a thin excuse to link to XKCD. Be sure to read the mouse-over text.

Commentary.

More succinctly, and in t-shirt form.

Homework 5, #7

By the way, here are a few code-based solutions that you submitted to homework 5 problem #7. Quite a variety - Fortran, C/C++, and Python are all represented.

My own (hastily-composed) version is here, in standard C. It should compile with vanilla gcc. It takes a command-line argument N, where N is how many terms of the harmonic series to evaluate. For "fun" I also included code (commented out) to calculate the same sum recursively.

For reference, here is the source of the problem (Car Talk), here is their answer, which employs the Euler–Mascheroni constant.

Physics of the Death Star

We won't cover gravitation until just before spring break ... but file this away for later.

Another great blog full of neat physics posts, highly recommended.

And on the lighter side of physics ...

Modeling the head on a glass of beer.

By the end of the semester, we should be able to do better. Of course, we will not have an associated laboratory experiment.