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Author Topic: Measuring Time  (Read 4196 times)

Offline Hooman

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Measuring Time
« on: November 26, 2005, 08:51:11 PM »
You have two ropes and a lighter. If you light one end of a rope it'll burn for eactly an hour. The two ropes however are of varying length and thickness, so the rate of burn is non uniform. How can you use these 2 ropes to measure out exactly 45 minutes?
 
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Offline zanco

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Measuring Time
« Reply #1 on: November 26, 2005, 09:04:31 PM »
Hmm... Just a question, do you really need to use 2 ropes for the measure?
Because you can only use one.

Well, you know that Rope 1 takes one hour to burn enterily, so if you cut that rope in half, this half will take 30 minutes. If you then cut the half in half, it will take 15 minutes. Now if you want to measure 45 minutes, take One half of your rope, light it and wait until it's all consumed (it will take 30 mins)then light the other half that you cut in half ...  :blink:  ... and wait until it's consumed (this piece will take 15 mins). There you have used Rope 1 to measure 45 minutes. Better yet, you can use the other rope (Rope 2) to strangle the evil monkey that lives in your closet... jk.
« Last Edit: November 26, 2005, 09:06:02 PM by zanco »
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Offline Betaray

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Measuring Time
« Reply #2 on: November 26, 2005, 09:11:20 PM »
hooman, where do you come up with this stuff?
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Offline Hooman

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Measuring Time
« Reply #3 on: November 26, 2005, 09:53:19 PM »
Sorry Zanco that won't work. The ropes are of varying width, so their rate of burn is non uniform. That means it might not take half the time to burn half the length of rope. It could easily turn out that half the rope only takes 20 minutes to burn, or it could take 40 minutes to burn. All you know is that the entire rope takes an hour to burn.

 
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Offline zanco

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Measuring Time
« Reply #4 on: November 26, 2005, 10:05:34 PM »
Oh silly rabbit, when you said
Quote
The two ropes however are of varying length and thickness, so the rate of burn is non uniform

I thought you meant somethink like the two ropes burn with a constant rate, but this rate differs from rope to rope.  :heh:



I, however, got another idea. I think even if the thickness and the width are different along the same rope, it will take exactely 1 hour if you light one end or the other of the same rope, right? Right!
So I take Rope1. I light both ends of Rope1 and one end of Rope2! This should take 30 mins to burn out Rope1, regardless of the point at which the two flames meet. When Rope1 has done burning, I light the other end of Rope2. Because Rope2 only has 30 mins of "rope-combution", if I light the other end, it should take 15 for the two flames to meet. And there I have used those two non-uniform ropes to measure 45 mins of earth time.  
« Last Edit: November 26, 2005, 10:13:50 PM by zanco »
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Offline Betaray

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Measuring Time
« Reply #5 on: November 26, 2005, 10:17:49 PM »
GET A WATCH!!

lol
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I am the nincompoop, I eat atomic bombs for breakfest, fusion bombs for lunch, and anti-matter bombs for dinner

I just hope they don't explode

Offline Hooman

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Measuring Time
« Reply #6 on: November 26, 2005, 10:22:26 PM »
Heh. Looks like Zanco has solved this one already. Well, nice work.  :)

(You didn't just google this one did you?)
 
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Offline zanco

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« Reply #7 on: November 26, 2005, 10:24:08 PM »
No, lol. Trust me, I didn't use Google. I just thought! I like those kind of riddles. I have tones of them here.
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if anyone finds and communicate to us that which thus far has eluded our efforts, great will be our gratitude.
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Offline Hooman

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Measuring Time
« Reply #8 on: November 26, 2005, 10:27:48 PM »
Ahh. I'm gonna have to dig up some harder ones then.  ;)  
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Offline HaXtOr

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Measuring Time
« Reply #9 on: November 27, 2005, 12:38:04 AM »
damn i like fire :whistle:  
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Offline CK9

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« Reply #10 on: November 27, 2005, 03:34:19 AM »
damn, two riddles I knew how to answer, but I didn't get a chance at wither one :(
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Offline Eddy-B

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Measuring Time
« Reply #11 on: November 27, 2005, 05:11:22 AM »
pretty ingenious
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Offline Hooman

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« Reply #12 on: November 27, 2005, 10:27:09 PM »
Yeah, I was hoping that one would stand unanswered a little longer. I rather liked that one.

Don't worry CK9, I'm sure you'll get your chance.
 
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