Pendulum experiment

garageband

Hi I'm supposed to come up with a design for a pendulum experiment. I have most of the design figured out but in regards to measuring the oscillation I don't know how to do it accurately aside from using a stopwatch to measure the oscillation(in which case the period would have to be really long). Also, with the pendulum experiment I was thinking of doing a coupled pendulum experiment as well or would it be too difficult. Thanks, btw, I'm in grade 12 I'm doing this as part of my Physics Experiment project.

atyy

Time lots of periods (say 30 to 100) with your stopwatch. Get the duration of one period by dividing by the total number of periods.

garageband

Okay that would make sense but is there another alternative because if I were to do that with the coupled Pendulum experiment I honestly don't know how I would go about doing it.

atyy

http://www.theorphys.science.ru.nl/p...endul-en.shtml

I'm not sure this will work, just guessing. Anyway, it seems that if you let one pendulum go with the other at rest, the other pendulum will also oscillate, and the amplitude of its oscillations will also oscillate (ie. its amplitude will get bigger then smaller then bigger, let's call this this the "envelope"). You could time the periods of the pendula separately, and also time the period(s) of the envelope (seeing where it goes to zero is probably easier than seeing where it becomes largest). From all these periods you can get their frequencies. Apparently the frequency of the envelope is related to the difference in frequencies of the individual pendula.

garageband

Thanks for your feedback. Well I will try it out if I get the design part working, but wouldn't this mean I'd have to measure the oscillation for each time or rather each period of the oscillation and for both of the pendulums? That would mean around 4 measurements for each period? Also in regards to the spring between the two pendulums, is there a certain distance in which it has to be proportional to the length of the string or no? I'm open to other ideas as well as how to approach this thanks again.

atyy

Yes, the periods of 4 different things (and 10 - 30 periods of each thing to get a good estimate). Maybe you don't have to set it up with a spring. fredwittel's setup http://www.youtube.com/watch?v=RoSYKPTdlxs seems to behave similarly to the blue and red traces in http://www.theorphys.science.ru.nl/p...endul-en.shtml. These are just my guesses.