MagLev C

[Balsa Man]

Yup, that was covered in a national rules clarification some time back. Go to http://soinc.org/frequently_asked_questions , use the dropdown menus to find the event. As long as the inside edge of your side rails is >2.0cm above the top edge of the magnets, you're good.
That said, don't be surprised if the centering/stabilizing effect you're thinking this will get you...doesn't happen. Earlier in the season we tried it. Intuitively, it seems as if it would work. Rather than putting magnets in this configuration, you might try a short section (just a bit longer than the vehicle) to check out actual behavior.

It's only a rough approximation, but if you imagine the field of each strip to be a tube, and the fields of the magnets on the vehicle to be tube sections, you can get a sense of the problem. If you set the vehicle on the track field tubes, very carefully centered, because of friction, it will sit there- be stable. However, take away that friction (the levitating interaction being frictionless), and its unstable- it will roll about the long axis. Our conclusion was that roll was inducing harder side rail contact (i.e., more "rail drag" friction), than a flat arrangement.....

[joeyjoejoe]

Not trying to stifle your creativity at all but we tried that and no matter what we did, the car twisted nearly immediately to one side or the other. If you figure it out I'd love to hear about it. We tried many different configurations including magnets on the outside of the track walls (which provided a lot of stability but failed the 2cm test that balsa man mentions). We later tried tilted magnets on the track and on the car. This took a little of the upward push from the repelling magnets and translated it into forward push so that, with no motor and a little push, the car would sail down the track. Unfortunately, the car must be able to travel both ways down the track and you can imagine what happened when we turned our car around. We had many failures but a lot of successes plus we really learned the meaning of the word serendipity!.

[Maxcamac11]

Well we've got time to experiment, so I'll keep updating on our progress. Quick question: Does it matter how the magnet's polarity is placed? For example, the diagram in the PDF guide on the SCIO website shows one row of magnets on the track as North and the other row as South. Is it legal to have both rows North and the magnets on the car both be North? And I can make the width of the track (from side rail to side rail) a maximum of three inches, right?

[Balsa Man]

Yes and yes.

[rg3thedon]

650 to 1100 for .95m? Why such a big range for .95m??
Our car is getting between 1200 and 1360 for .95m but I'm betting the upper score is due to timing errors. We don't have any optical sensors, just a thumb on a stop watch and when you're talking about times around one second, it is easy to make an error.

Can you guys include the car's weight and time it took for the car to travel 95 cm? I was curious when I saw joeyjoejoe and twototwenty. Did your cars weigh 400g and take .4 seconds or more like 1500g and take 1.5 seconds?

[twototwenty]

650 to 1100 for .95m? Why such a big range for .95m??
Our car is getting between 1200 and 1360 for .95m but I'm betting the upper score is due to timing errors. We don't have any optical sensors, just a thumb on a stop watch and when you're talking about times around one second, it is easy to make an error.

Can you guys include the car's weight and time it took for the car to travel 95 cm? I was curious when I saw joeyjoejoe and twototwenty. Did your cars weigh 400g and take .4 seconds or more like 1500g and take 1.5 seconds?

Definitely (for me anyway) the former. I don't know about joeyjoejoe, but I have a rather good motor/battery combination which allows the car to go quite fast, but I couldn't imagine getting a 1.5 kg car down the track quickly enough to get a good score.

[joeyjoejoe]

I'm not telling how our car still floats at this weight (see my comment regarding experimental serendipity above ) but our car gets around .95 seconds for .95m while weighing 1426 grams.
At 1769 grams it gets just over a second, which yields a better VS but is just too dangerous as the props are literally 2mm from either side wall. A while back, our car weighed app 500 grams and we were getting times in the .4-.6 second range (verrrry diff to measure) but the car was so out of control that we would occasionally lose props due to its erratic behaviour.

[monkeyman144]

Has anyone been able to find any practice tests? I have been looking but so far I haven't found anything.

[JTMess]

Has anyone been able to find any practice tests? I have been looking but so far I haven't found anything.

There aren't any I've seen online, but all the ones I've taken have been questions very similar to those in AP Physics textbooks and on the AP Physics C Exam.

[joeyjoejoe]

I know the rules state that the test is to be taken by the team but does that imply that the team takes the test together or both member get their own test?
Either way, the team takes a test.