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# Castle

93 replies to this topic

### #71 holla

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Posted 18 March 2008 - 01:38 PM

I would just put 1 bridge across the corner and the other from the middle of that bridge the edge of the island. Like so:

This will not work as the maximum length you can achieve with this approach is 9.5 + 4.25 = 13.75
As illustrated below in the picture.
Since angle and A and B are same, the sides AC and BC has to be same.
AC is half of max length of bridge, which is 9.5/2 = 4.25.

Edited by holla, 18 March 2008 - 01:40 PM.

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### #72 holla

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Posted 18 March 2008 - 01:53 PM

This will not work as the maximum length you can achieve with this approach is 9.5 + 4.25 = 13.75
As illustrated below in the picture.
Since angle and A and B are same, the sides AC and BC has to be same.
AC is half of max length of bridge, which is 9.5/2 = 4.25.

Sorry, I wrote saying this will not work based on some arithmetic, but then I realized that I made a simple mistake while halving 9.5 :-(
I was not able to delete the post.
This is the perfect solution. My apologies.
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### #73 woofy

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Posted 24 March 2008 - 08:49 PM

I like fosley's solution as compared to the "normal" T solution, but I believe he made an error in the following statement:

[quote name='fosley' date='May 14 2007, 04:11 PM' post='454']

."...... I'm not sure of the exact physics, but I know that the maximum mechanical disadvantage for the guy holding the board down is 10:8, or 1.25, and that would occur when someone was standing at the very opposite edge of the moat. So 2 guys on the end away from the castle would be sufficient for 1 guy to cross the bridge."

I believe only ONE person outside the moat could hold up to 5 people crossing the bridge built like this(assume the boards can hold them, don't flex and weigh nothing). His mechanical advantage is smallest at the end of HIS board or 8/1.5 = 5.33x. As the weight/people move away from the end of his board(on the other board), his demand gets lower since the weight will be increasingly supported by the ground on the opposite shore.

Thanks again for this different solution.
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### #74 xBluexEyesx

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Posted 29 March 2008 - 04:40 PM

im not altogether sure what i should think about your little diagrams and the fact that you (fosley) took so much time and effort to write an essay and do proper diagrams to explain your theory.

however, my first thought on solving this one was the same as undeniable's.

does anyone actually know the correct answer or shall we forever be in suspense???
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### #75 rookie1ja

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Posted 29 March 2008 - 09:06 PM

im not altogether sure what i should think about your little diagrams and the fact that you (fosley) took so much time and effort to write an essay and do proper diagrams to explain your theory.

however, my first thought on solving this one was the same as undeniable's.

does anyone actually know the correct answer or shall we forever be in suspense???

I do know the correct answer and I wrote it in the very first post
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### #76 sevenwolves

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Posted 07 April 2008 - 09:08 AM

put one bridge over the corner and put another board on thar board so you decreased the length of the moat at the corners. so you pretty much made a "t" shape at the corner.
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### #77 thermalguru65

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Posted 09 April 2008 - 12:35 PM

lay one foot bridge across the corner of moat, then place another from center of that foot bridge to inside corner of moat
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Posted 14 April 2008 - 08:41 PM

Castle - Back to the Logic Puzzles
A square medieval castle on a square island was under siege. All around the island, there was a 10 metre wide water moat. But the conquerors could make foot-bridges only 9.5 metres long. Nevertheless a wise man was able to figure out how to get over the water. What do you think was his advice?
(There's a place on the other side to put the bridge against, not just a sheer wall. the water moat has square corners - that section of the moat is about 14.1 metres wide.)

Spoiler for Solution

could you not tie two ends together to span the moat like a folding ladder?
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### #79 jimmyc

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Posted 20 April 2008 - 06:06 AM

you place one of the bridges on a corner forming a right triangle with the legs, the shore and the hypotenuse, the ladder then take another bridge from the middle of the first bridge over to the pint on the other side of the moat. the distance you gain from the first bridge shortens it enough for the second to span it.
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### #80 The-Xomix

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Posted 24 April 2008 - 06:48 PM

I would guess that the moat isn't a completely straight line so a possible example is this:

Bear in mind its 10m at the top, so you must throw the wood down halfway (appr.) and then climb up a bit!
Solved!

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