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#201 |
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Banned
Join Date: Jul 2008
Posts: 120
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Yeah it is a physics riddle. But this thread is home to riddles of any form
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#202 |
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FFR Simfile Author
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Ah, physics riddles. I remember no one was able to solve this puzzle last time I posted it, so maybe I will post it again.
Assume that gravity on or near the airless surface of a certain planet called FFR is such that any free-falling object will reach a velocity of 10 meters per second after one second, 20 meters per second after two seconds, 30 meters per second after three seconds, and so forth. Suppose a frictionless pulley (i.e., a wheel with a grooved rim that, once in motion, does not slow down due to friction), having negligible mass, is attached to a sturdy beam at the top of a vertical, airless mine shaft, and an inelastic rope 1000 meters in length but of negligible weight is threaded through the pulley with identical buckets of negligible weight dangling at each end. In one bucket are fifty stones weighing 1 kilogram apiece and an alien named Rubix weighing 50 kilograms, while in the other bucket is a single stone weighing 50 kilograms and an alien named Reach weighing 50 kilograms. Suppose Rubix commences dropping stones out of its bucket at a rate of one per second. The instant the first stone is dropped, Reach commences climbing the rope directly above its own bucket at a rate of one meter of rope per second. If Rubix starts at rest at a position 20 meters below Reach, how many stones will it have dropped the instant the two buckets are precisely side by side?
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#203 |
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FFR Player
Join Date: Sep 2006
Location: it's a mystery oooo
Posts: 3,221
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I got an answer of eleven stones to the above riddle. I'm confident in that value for the steps taken, though I wouldn't be surprised if it is incorrect (just look at the last time I gave "eleven" as a riddle answer). 8D
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#204 | |
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FFR Simfile Author
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I think I know how you got that answer though, and you're not entirely far off.
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#205 |
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FFR Player
Join Date: Sep 2006
Location: it's a mystery oooo
Posts: 3,221
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After incorporating the 1 m/s climbing rate factor into my calculations, I arrived at a new (and hopefully closer/correct) answer of seven stones. If that figure is wrong, it means I'm missing a critical component somewhere in my operations. =/
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#206 |
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FFR Player
Join Date: Jun 2006
Location: monteal
Age: 30
Posts: 188
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16?
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#207 |
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FFR Simfile Author
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Both are wrong.
Given I am right in assuming what you did initially to get your first answer, you were closer then. However, you could have came up with that answer a different way than what I'm thinking. If it's any condolence, I gave the problem to someone with their masters in physics and they couldn't get it. It's more about the logic of your approach than anything else.
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Last edited by Reach; 08-6-2008 at 10:31 PM.. |
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#208 | ||
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Private Messages, please.
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Just before dropping the thirteenth stone they should be almost exact assuming that Rubix is at the bottom end of the rope. I've got almost no logic whatsoever but it isn't a random guess.
-o24
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#209 |
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Banned
Join Date: Jan 2008
Posts: 311
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EDIT: Just answered my own question
Last edited by QuadDamage; 08-7-2008 at 11:00 AM.. |
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#210 |
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Banned
Join Date: Jan 2008
Posts: 311
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Hm initial calculations give me around 27 stones, but that seems way off to me.
Will take another look at it later -- not confident in my answer. It's been a while since I've messed around with pulleys/tensions/ropes and that sort of thing. I'm making the assumption that initial acceleration is 0 and that acceleration is uniform for both sides once the masses are no longer equal (as it wouldn't make sense to me otherwise), and I'm making the assumption that distance traveled per second is half the acceleration (for a second's timeframe, that is. Also, the acceleration changes every second). I'm also assuming that the fact Reach is climbing is irrelevant since the total weight is always going to be 100 kg. I'm therefore assuming that each side needs to travel 10m since accelerations are equal, and so I'm basically figuring out the summation of distances traveled until both sides travel 10m as a function of their accelerations. Changing a few of these assumptions also gets me around 22 stones, but again, not confident. Gonna look into this problem more when I get a chance. Last edited by QuadDamage; 08-7-2008 at 12:11 PM.. |
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#211 |
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FFR Simfile Author
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No correct answers thus far.
How is this thread going to continue given Rubix's account for this thread is banned >_> I quite like puzzle threads.
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#212 |
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FFR Player
Join Date: Jul 2008
Posts: 1
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Well i think Two stones will be dropped before the buckets pass each other..
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#213 |
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FFR Player
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#214 |
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FFR Simfile Author
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I knew that.
QuadDamage can't edit the first post now can he? I suppose Rubix can continue to post riddles within the thread like myself, but that isn't nearly as convenient.
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#215 |
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FFR Veteran
Join Date: Jul 2007
Location: Retired in the distant land of Canadia
Posts: 1,597
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Get Rubix to make a new thread with his QD account...by the time it gets banned for ban-evading, his original account should be unbanned.
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#216 |
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Banned
Join Date: Jan 2008
Posts: 311
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My original is permabanned.
Anyways, new riddle for you guys: On the FFR island, weather is either sunny or snowy, and follows these heuristics: If today is snowy, the chance of snow tomorrow is 50%. If it's sunny today, the chance of snow tomorrow is 80%. So if it snowed today, what's the probability that it snowed yesterday? Last edited by QuadDamage; 08-8-2008 at 09:18 AM.. |
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#217 |
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FFR Veteran
Join Date: Jul 2007
Location: Retired in the distant land of Canadia
Posts: 1,597
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Wait, what? You got permabanned for posting an in-before-lock gif? That's a bit extreme.
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#218 |
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Banned
Join Date: Jan 2008
Posts: 311
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The additional bans came from me making extra accounts in order to view the forums.
I should add though I was also having an extremely bad day, as my doctor pretty much told me that if I wanted to keep my hands functioning, I'd have to pretty much kill off my hobbies (I have many and they're all hand-intensive). Also was upset that the initial ban cut into my subscription. Last edited by QuadDamage; 08-8-2008 at 01:41 PM.. |
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#219 |
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FFR Player
Join Date: Jun 2006
Location: monteal
Age: 30
Posts: 188
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65%
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#220 |
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Banned
Join Date: Jan 2008
Posts: 311
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tuv: And your logic is...?
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