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Oops, after a little more thought (darn SI units!) our car weighed 1487grams which is actually only 3.25lbs. We get around a second for .95m.
We were getting roughly 10% better times until I finally decided we should take the wheels off of the corners of the cars despite it being OK'd by the latest rules clarification. I didn't want to make any waves.

joeyjoejoe wrote:Oops, after a little more thought (darn SI units!) our car weighed 1487grams which is actually only 3.25lbs. We get around a second for .95m.
We were getting roughly 10% better times until I finally decided we should take the wheels off of the corners of the cars despite it being OK'd by the latest rules clarification. I didn't want to make any waves.

We've been getting comparable scores for that distance. Interesting choice for the wheels. Did they help with the static friction for the initial start-up of the vehicle?

blakinator8 wrote:

Flavorflav wrote:I must say that that doesn't seem like a very good test. I have seen ceramic magnets claiming 20 lbs of pull, small enough that six could probably be placed on a vehicle - which would then be quite difficult to remove from a plate. The 5 lb variety is pretty widely available, and even six of those that would not be easy.

I agree with this entirely. It isn't hard to find ceramic magnets with 6-9 pounds of holding force, 8-10 of which could be placed on a single vehicle. It would basically be like trying to lift a 60 pound weight.

Which illustrates part of the reason for having this test in the first place. What if your finger accidentally gets caught between the vehicle and a metal object? The prohibition on rare earth magnets is for 2 reasons: first is general safety, they are just too dangerous due to the significant strength they can exert, particularly when coupled together. the second reason is that when used improperly, they can demagnetize a maglev track very quickly, effectively ruining that track. If you can't easily remove the vehicle from the test plate, and you are sure you aren't using rare-earth magnets, you are going to have a lot of explaining to the event supervisor as to why your vehicle isn't in violation of general rule #5 which prohibits unsafe items.

I have to admit I don't do the test portion of this event, but what's the physics behind demagnetizing a magnet with a stronger magnet? Is it just because of the difference in field strength or is there some other interaction going on?

Hey guys. I have a quick question.

Can I strap a remote control helicopter onto the car to power it down the track with the remote? Our can it only being non remote control, or infrared only?

Thanks!

Well, firstly it cant have integrated circuits, which pretty much rules out remote control. Secondly, do you have a copy of the rules? Your coach should've gotten one when they registered your team with the state, the rules have a lot more specifics concerning what your vehicle needs to meet specs.

chalker wrote:

blakinator8 wrote:I agree with this entirely. It isn't hard to find ceramic magnets with 6-9 pounds of holding force, 8-10 of which could be placed on a single vehicle. It would basically be like trying to lift a 60 pound weight.

Which illustrates part of the reason for having this test in the first place. What if your finger accidentally gets caught between the vehicle and a metal object? The prohibition on rare earth magnets is for 2 reasons: first is general safety, they are just too dangerous due to the significant strength they can exert, particularly when coupled together. the second reason is that when used improperly, they can demagnetize a maglev track very quickly, effectively ruining that track. If you can't easily remove the vehicle from the test plate, and you are sure you aren't using rare-earth magnets, you are going to have a lot of explaining to the event supervisor as to why your vehicle isn't in violation of general rule #5 which prohibits unsafe items.

Since the event rules only mention not using rare-earth magnets then wouldn't a receipt or original packaging be enough to show that they are non-rare-earth magnets. Would this be enough to support that they are not the rare-earth magnet type?

While I agree that general rule #5 prohibits the use of unsafe items (spinning fan blade ), don't forget General Rule #2: Unless otherwise stated, if items are not excluded, they are permitted unless they violate the spirit of the problem. This is just a case of the teams designing something within the boundaries of the rules they were given and has nothing to do with their misintrepretation.

It would have been different if the rules had said something about this steel plate test instead of just saying "rare-earth magnets".

iwonder wrote:Well, firstly it cant have integrated circuits, which pretty much rules out remote control. Secondly, do you have a copy of the rules? Your coach should've gotten one when they registered your team with the state, the rules have a lot more specifics concerning what your vehicle needs to meet specs.

Where does it say that in the rules? I found a copy online, and i don't see anything about integrated circuits anywhere. Can someone show me where it is?

cifutielu wrote: Where does it say that in the rules? I found a copy online, and i don't see anything about integrated circuits anywhere. Can someone show me where it is?

Try 3j.

blakinator8 wrote:

cifutielu wrote: Where does it say that in the rules? I found a copy online, and i don't see anything about integrated circuits anywhere. Can someone show me where it is?

Try 3j.

I see. Thanks!

So how would you make a motor that would run with rc run at max speed when a switch is turned on?