I think it's centrifugal force that elongates the string--centripetal would be the force that helps the car accelerate to higher speeds while tethered to a central point. Something like that.

I can't remember, this is why I'm not an engineer.

Love it! Its got a great beat and you can dance to it.

Just don't get your legs caught in the cable.

ash78
But didnt you play an engineer on TV?

@htrodblder: Nope. Holiday Inn Express. Or maybe it was the wayback of a Vista Cruiser.

I'm not sure I get the point of this, but that is damn fast. That tether breaks, and that is one hell of a projectile.

@ash78:
Having an engineering degree, and not being able to remember the difference has me happy to be working in finance.

What kind of nerds build a giant track for this? I wonder how many of them are married? How many of them do you think have Star Trek uniforms?

@ash78: I believe that centripetal is correct here, as it describes the wire pulling the car toward the center of the circle. Centrifugal force acts upon something in the car (the fuel, say) which is trying to move in a straight line but cannot because the car is being pulled away by the wire. It seems to me to be a function of inertia.

I've seen a couple of these - it looks hellaciously fast and you think that's all she wrote...then the little motor gets on the pipe, hits its torque range, and all the demons come out to play.

@rlj676: Good thing us physicists are around to set y'all straight. An object in rotational motion (the car) does exert an equal and opposite force, the centrifugal force, to the centripetal force exerted on the object (i.e. by the wire). There is also a fictitious centrifugal force but that's not an issue here.

@ash78: It's all semantics. Centripetal and centrifugal forces are one and the same. Depending on to whom you are speaking.

A Physisist will tell you that centrifugal force doesn't exist.

Practically speaking, both exist, and both rely on each other. One is reactionary to the other.

The force the tether imparts on the car is centripetal. The force the car imparts on the tether is centrifugal.

@BLS: Storm Trooper uniforms are way cooler.

Literally - there's room inside that shell, and you can mount CPU fans.

Hey, you want some anachronistic nerdliness? If I can find it, I'll post the Steampunk R2D2 - it's a steam-powered, radio-controlled R2 unit. He moves, turns, and billows clouds of vapor.

Centrifugal force is not a real force, it is only a perceived force.

@Ben Wojdyla: Kid, I've flown from one side of this galaxy to the other, and I've seen a lot of strange stuff, but I've never seen *anything* to make me believe that there's one all-powerful Force controlling everything. 'Cause no mystical energy field controls *my* destiny. It's all a lot of simple tricks and nonsense.

@smalleyxb122: @Ben Wojdyla: Yeah, just chiming in and agreeing, centrifugal force is the percieved force that results from a force balance with centripetal force (which is real). And there's hardly any element of radio-controlledness here, it's just an engine and some wheels tied to a string going 200mph in a circular track.

Centrifugal force is what your Momma threatened you with if you didn't eat your veggies.

@elwood:

I too found a real lack of radio controlling. Is there even a speed control, or is it just on full tilt with high gearing judging by the push start.

@Ben Wojdyla:

[imgs.xkcd.com]

IF that doesn't convince you of the existence of the centrifugal force, I don't know what will. If there was no centrifugal force, centripetal force would upset the equilibrium of the system.

Oh, and 200 mph? Seriously, I hope they use one hell of a load-tested wire : the skewed catenary caused by wind resistance acting on the wire would amplify the tensile forces by some magnitude ...

That's actually a very old hobby, started in the 1930s. There even is an American Miniature Racing Car Association (or NAMBLA), founded in 1940. Apparently, there are tracks in all corners of the world... And no, not radio-controlled. Just a tether. And l thought I was weird.

This makes so much sense... NOT!

If you watch the sky in the video you will see birds fly by but they are flying much too fast, in a time lapse sort of way, so I say part of this video is bunk.

@Vega: *rofl*

@Tiemco: apparently somebody doesn't read text too well, those are bugs friend, and watch the flag - it would wave oddly if the video was sped up.

@smalleyxb122: Prewisely!

Maybe I'm a bit of a pussy but I do NOT think I would be standing where that guy filming that was standing.

Sure, why not a 200mph model car... It looked like one of the land speed record attempt cars. And probably less wind resistance as it is so small.

@Vega: Uh, I think you've got your membership cards mixed up.

There's also competition for speed records for model airplanes - bot h radio controlled and control line. According to the FAI, the current record holder's speed is 395.64 km/hr ([records.fai.org]) . My math is kinda fuzzy, but that's damn fast. And yes, that's for control line aircraft. That means standing in the middle and turning with the airplane....

@ET had a Cartruckgasm: To end such discussions: [en.wikipedia.org]

The only drawback is that when the car reaches a certain speed at its mass, it skips through the time/space continuum and ends up unassembled, waiting to get loaded and onto the track. That's why people who start this hobby can't abandon it.

@beercheck: I've been looking for a chance to use that Daily Show running gag for ages. Today's my big day!

I hope no Tribble's find their way onto the track.

@Vega: Thank god... Well played, then. Well played.

I'd love to see what would happens if the guy stepped off the pedestal while the car is running. It'd be like watching a scaled up Magimix dealing with a salami.

Anyone remember the film Runaway with Tom Selleck? Those nifty little remote controlled bombs they used on the freeway to drive under cars and swiss cheese them?

Veyron drivers watch out..

(and if anyone did ever work out how to make a moustache seeking missile, I'm sure you'll have a list of customers. Apply c/o Mr Selleck..)

You call yourselves car guys?
And you never heard of tether cars?
Hell, your grandpa probably played with them back in the 50's.

@saabophile2: Sweet, I was thinking it was the opposite of centrifugal. I must have larnt something in college after all. Actually, it's the remembering that is hardest. The learning is easy...

@studemax: I've heard of tether balls, does that make me a ball guy?

I had tether cars with 049 engines and I was born in 71.

The fact that the speed changes dramatically shows that there is some form of remote throttle control, and there is nothing to indicate it's not radio.

Regardless, that is a fricking fast model car.

There is a video of someone sitting on a platform above one of those central poles and he falls off into spinning cable. I saw it a few years ago right after seeing this video first time. I'm too lazy to search for it, but it's out there.

So, if the wire goes 'sproing!' is that bent 2x6 enough to hold all the parts in?

@saabophile2: If I understand correctly, the fictitions centrifugal force appears when your frame of reference is rotating and you start mis-labeling things. The example on the Wikipedia page that worked for me was the car going around a turn example, where instead of a force pushing you outwards, your inertia is keeping you moving in a straight line and the car is moving in to meet you, and the force that people say pushes you out in a turn is the fictitious centrifugal force.

Imagine trying to play hopscotch with that tether.

At that speed, you could become a lot shorter if you didn't keep up.

I like the doppler effect going on here.

@philibuster: Gotta throw that one in to keep up with the science geeks?

Nobody ever writes songs about nitro-burning tether cars.

@The fact that the speed changes dramatically shows that
there is some form of remote throttle control

There is not. These tiny two-stroke engines just have very highly resonant tuned pipe exhausts, which give them an immensely peaky RPM-to-power graph.

Tether cars, like the old non-RC Cox-motor model planes, just run at full throttle until their minuscule fuel tanks (built into the motor assembly) are exhausted. There isn't even a way to throttle these engines without modifying them.

Anyone else curious about how this car would do at Bonneville?

Now someone get out there and do it with a full scale car. Cable it up, and put a brick on the gas.

It's the world's coolest weedwacker.

@Vega: NAMBLA...hahaha!
That's as funny as South Park a few weeks ago...the World Canadian Bureau or (GBT) or whatever acronym they used...too funny...

Funny how man boy love assoc sounds like american radio controlled racing society....

mini nascar.

At the midnight NAMBLA
The tether car is the nemesis of the toddler.

For full effect should be written in Old English script.

What is the radius on that circle? I'm guessing about 30' or so, but does someone know? If it's 30', and the car is actually hitting 200mph, that's about 90 lateral g's. Yikes.