Gooblah wrote:1) Would one be allowed a calculator, if an irregular period (as invariably would happen) existed for counting purposes?
Nope, you're not allowed to use a calculator at all for the first part of the competition. It's really dumb in my opinion--if you can use an electronic balance for a water clock, why can't you use a four-function calculator for the pendulum? It's not that difficult to just multiply it out, though, in the minute you get between launches. Just make sure you double check.
Now, the first year I did this event, I neglected to read the rules where it said you couldn't use a calculator for Part I. And apparently so did the event supervisors at regionals, so I got away with using it. Ironically, this year, the regionals guy was even worse. The test said "only four-function calculators allowed" (and this is one of the few events where you can use a graphing calculator), but when I told him he could have cared less. He forgot to impound watches, too, until I reminded him...
Gooblah wrote:2) How would one measure tenths of a second with a pendulum? It seems like one would be just guessing at some point...
Yeah, it is. You can get pretty accurate, though, because of the way period is measured. Say you've got a pendulum with a period of exactly one second. (It's a little unrealistic to calibrate something so precisely, but it would be about 10 inches long.) That means that the outswing is half a second, and the backswing is half a second. You can easily subdivide these in half, because you can see if it's passed the equilibrium position or not.
That's an error of .25s at most, which isn't bad at all for the last four trials. For the first trial, you might want to use a pendulum with a period of half a second, which means your error would be around .125s. Conservatively, We'll say the average error is somewhere around .2 seconds per trial, except for the first. Scoring that yields (1 * .4) + (2 * .3) + (2 * .2) + (2 * .1) + (2 * .1) = 1.8, giving you a score of 48.2. That's a win at regionals.
Bogoradwee wrote:seeing as i haven't tried a pendulum, i can't entirely answer your pendulum question, but i can imagine that they could have attached some thing that the pendulum's path would line up with and it could have markings, allowing specific regions to be specific tenths of seconds.
You could definitely experiment with something like this, but I would say don't bother. You just won't have time to make such an intensive calculation in a minute. I wish you could bring a chart or something, but you'd have to bring one for each angle--that's like 45 of them. Spending some quality time with your pendulum will be much more beneficial in the long run. You'd be surprised how accurate you can be once you get to know it.