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[ed boy]

I'm reviving this thread with a variation in a previous puzzle.

The original puzzle was:

Here's one for you:

There an infinitely long train line, with a station every mile. Somewhere on this train line is a train. You are told the following:
-The train's speed is constant
-The train initially starts at one of the stations
-One hour later, the train passes through another station

You are tasked with finding this train. You are given a magical telephone that allows you, once an hour, to phone up a station and ask the station manager if the train is currently there. You are also, for the purposes of this exercise, immmortal, so you will be able to do a lot of phoning the stations.

How will you use the above to find a method for predicting which stations the train will visit, and when?

However, in this new puzzle, the question you ask the station manager is different. You can only ask him if the train has, at some point in the past (or present), passed through the station. You only get a yes or no answer. You cannot ask the direction, or how long ago it was, or how fast it was going.

[Urist Imiknorris]

I call a random station, and ask. If the train has not passed through, I call the one after that. If it hasn't passed through there, I call the third one before the original random station, and if that fails, the fifth after, then the seventh before, and so on until I receive a "yes" answer. I then call the last station in that direction that I called four times.

-If the first answer is "no," and a subsequent answer is "yes," then the train is there and traveling toward the original station.
-If the first answer is yes, then I call the station two closer to the original, and repeat (calling two stations closer each time) until I get a no. I then call that one twice. If either is a yes, then the train's there, heading toward the original station.
-If all four calls result in a "no," I call each of the four stations between the one I just called and the one that originally gave me a "yes." Once I get a "yes," I count how many calls I made total, and call the station <that number+1> further away from my original. The train will be there, heading away from the original.

There's probably a simpler way, but it works.

[ed boy]

That won't necessarily work. Let the station that you chose arbitrarily be at position A. If the train started at position A+1, and moved at a speed of 2mph in the positive direction, then you will never get a 'yes'.

[Urist Imiknorris]

Oh yeah, misread the problem. HERP

[TheBeardyMan]

What is the next number in the following sequence?

1, 2, 4, 6, 16, 12, 64, 24, 36, 48

[MonkeyHead]

1, 2, 4, 6, 16, 12, 64, 24, 36, 48, 1024, 60, 4096, 192, 144, 120, 65536, 180, 262144, 240, 576, 3072, 4194304, 360, 1296, 12288, 900, 960, 268435456...

[Il Palazzo]

edit: derp. Nevermind, I have already asked this question earlier.

[ed boy]

A new one:

You go to the local shop, and buy yourself the following:
1kg of feathers
1kg of gold
1 perfectly accurate set of scales

You then go home, and set up the scales. You put the feathers on one side and the gold on the other. What happens?

[Vector]

Presumably, the scales balance, unless you mean that the low density of the feathers causes them to get all over the place including up your nose and you can't really get them ON the scale.

[alway]

Depends on whether the 1kg includes enough to balance out buoyancy from the air. If it's 1kg as measured in a vacuum, the gold would appear to weigh more as it would have less buoyancy due to having a higher density/lower volume.

[ed boy]

Depends on whether the 1kg includes enough to balance out buoyancy from the air. If it's 1kg as measured in a vacuum, the gold would appear to weigh more as it would have less buoyancy due to having a higher density/lower volume.

Bingo.

[Vector]

. . .

Yeah, I'm going to keep out of this thread until I have more than the most elementary of physics knowledge ^_^;;

[PsyberianHusky]

Why does it always have to be snakes?

[Strife26]

Rule of drama.

[Korgus]

A new one:

You go to the local shop, and buy yourself the following:
1kg of feathers
1kg of gold
1 perfectly accurate set of scales

You then go home, and set up the scales. You put the feathers on one side and the gold on the other. What happens?

I've heard this one, but I think it only works with pounds. They're measured in different units, so the feathers are heavier.