# Could you cross a series of moving tracks that get progressively faster and then slower?

Asked by Ltryptophan (10286) June 28th, 2010

Let us say there are odd number x sets of tracks laid next to each other. The tracks make an n mile loop. They are laid concentrically one closely within the next.

Upon each track is a platform, or series of flat cars that are moving at varying speeds. Each track, with the exclusion of the center track is moving at the exact same speed as the track that is equally distant to the center track on the far side. The moving platforms are so close together that only a half inch separates one from the next.

There is a docking platform within the loop of the tracks, and along the outside of the tracks. The tracks that touch the docking platform are travelling at a slow enough speed to step onto them without losing your footing. As you walk across to the next track approaching the center the speed of the tracks very gradually increases until it is fastest at the center, and then begins to decrease at the same interval as you go out from the center towards the other side.

If the center track is moving at 200 mph, can you cross to the other side on foot?

Observing members: 0 Composing members: 0

We walk around in 600 mph airliners, so I don’t see a problem on the center track.

So I vote “sure”.

jaytkay (25767)

Sounds like a job for the mythbusters! Send in your idea to their site.

@jaytkay The difference being that the air inside the airplanes is moving at the same speed that we are. When someone’s moving relative to the air at 200 mph, there’s going to be a lot of air resistance, probably enough to knock them over.

Mariah (25831)

I don’t see a problem, it all depends on the speed difference from one lane “track” to the next.

As long as Y < S + r

Y=Speed difference between tracks, (mph)

S=Your maximum pounce, jump, run, walk or step speed (mph)

Depending on what the rules/conditions are, and if in fact, A. The platforms are big enough for you, so if you fall down, you won’t fall off of the platforms. B. What the starting position is
1. if you are standing still, then the number of tracks have to be 200mph/z
2. if you are starting out on a moving platform, then the same rule applies

The goal would be not to get ripped in half.

BTW, I much rather call the “Tracks” Lanes so there are no confusions.

http://tinyurl.com/hy9yh

http://tinyurl.com/2748qk9

windex (2932)

@Mariah When someone’s moving relative to the air at 200 mph, there’s going to be a lot of air resistance, probably enough to knock them over.

Dang. I change my vote – Nope.

jaytkay (25767)

What if the center track were going slow enough to allow for walking, but not slow enough that if it were the first track you could board it.

Ltryptophan (10286)

@Mariah @jaytkay It does really depend on the shape of the cars—if the cars are such that there is a “bubble” of low speed air around the car (think the inside of a convertible), you could step as long as the relative velocities are low enough to make the step.

The top speed doesn’t matter, although the local air speed does.

Sort of related is a show I was head rigger on. We had an aerialist doing various tricks, but one of the more difficult from our perspective was “air running”—Him, holding onto silk, would run in a large (~50 foot radius) circle, and leap off the front of the stage, we’d haul him up a bit so he would clear the audience. Most of the time he was flying around pretty close to a sprint speed (minus a little air resistance).

The ending ,when we were feeling good, was to drop him back down onto an 8’ wide “runway” that projected out into the audience. There were audience quite close to this runway, and we had very limited time to abort if he didn’t stick his landing. Consider this: he was flying at around 8 feet per second, and so we had maybe a half second window in which to (gently) touch him down onto the runway. If we missed the window we had to haul him back out another 5 or 6 feet to clear audience heads, and loop him onto the main stage where we had a good 50 feet to land him in.

grumpyfish (6630)

Whoa! Google tells me a low-speed version of this idea was built – 117 years ago!

The first moving walkway had been unveiled eight years earlier at the [1893] Chicago World’s Fair and had proved a huge success at subsequent expositions in Berlin and Paris. Chicago’s walkway, the brainchild of engineer Max Schmidt, consisted of three rings, the first stationary, the second moving at 4 kilometres per hour and the third at 8 km/h, an arrangement that allowed walkers to adjust to each speed before moving to the next.

Here’s film from the 1900 Paris installation:

jaytkay (25767)

Excellent jaytkay! I feel like as though you gave me a birthday present.

I think this could solve some transportation problems, maybe in congested cities.

Ltryptophan (10286)

Maybe there is one somewhere today still in use!

Ltryptophan (10286)

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