93 replies to this topic

[manisdogfish]

You could just set up a village around the castle. Eventually the people in the castle will have to come out. They're going to need to come out for fresh water within a week easy.

This answer reminded me of the movie Kagemusha by Akira Kurosawa. Not necessarily...they might not have to come out.

[wtfbananas]

okay...so if the longest distance between two points is a straight line...how bout they just build an arch.....

[owlpost]

If you made the bridge out of wood it would float.

[BoilingOil]

First, about the post above mine, I don't know if I'm overlooking something, but why do you say 8.5 unit thength of bridge is being used to complete the diagonal bridge when the bridges are 9.5 and not 8.5 meters long?

Oooh, that's a simple one... A board of 9.5 metres length can not bridges a 9.5 metres moat, if it can't firmly rest on something like solid ground, can it? The assumption was therefor, that 1 metre of the board rested on the ground or on another board, probably 0.5 metres on either side

BoilingOil

[harvey45]

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

that's what's on the solution up top, you didn't need to put that on here.

[Hathawulf]

I didn't get where it said how wide the foot bridge could be... If it was 4m wide, then you put the plank at a diagonal, it would touch and you can cross between the opposite points of the plank.

a 9.5m long x 4m wide is 10.3m from corner to corner.

[ali500]

let's say it IS an army and not just any army it the DA from JK Rowling's 5th Harry Potter book they could just use magic. I know that can't happen but if it were a normal army half jumps the .5 meters left (the ones who are good at track) the other half stand on the other side of the bridge so it stays on land. The half that don't attack the castle keep watch on case the castle has an ali on land and they make sure the ali dosen't get into the castle.

[Mikel278]

The calculation is correct and this solution would work, IF and only IF the bridge was really thin. But, unless the people are tightrope walkers, you would probably assume the bridge is maybe a half meter thick. If that is the case, then you would have to move the angled bridge (the first one) half a meter in towards the corner. Otherwise, you would not be able to secure both sides of the width on the land. And if you don't secure the two ends, then it won't support the the second bridge. Also, if both sides of the width aren't secured, then the bridge wont stay flat, and you wouldn't be able to walk on it anyway. Unless we are dealing with an army of tightrope walkers.

[rookie1ja]

The calculation is correct and this solution would work, IF and only IF the bridge was really thin. But, unless the people are tightrope walkers, you would probably assume the bridge is maybe a half meter thick. If that is the case, then you would have to move the angled bridge (the first one) half a meter in towards the corner. Otherwise, you would not be able to secure both sides of the width on the land. And if you don't secure the two ends, then it won't support the the second bridge. Also, if both sides of the width aren't secured, then the bridge wont stay flat, and you wouldn't be able to walk on it anyway. Unless we are dealing with an army of tightrope walkers.

right

[joelbernardo03]

The calculation is correct and this solution would work, IF and only IF the bridge was really thin. But, unless the people are tightrope walkers, you would probably assume the bridge is maybe a half meter thick. If that is the case, then you would have to move the angled bridge (the first one) half a meter in towards the corner. Otherwise, you would not be able to secure both sides of the width on the land. And if you don't secure the two ends, then it won't support the the second bridge. Also, if both sides of the width aren't secured, then the bridge wont stay flat, and you wouldn't be able to walk on it anyway. Unless we are dealing with an army of tightrope walkers.

for anyone who wants to see the calculations:

laying the 9.5 m bridge across the corner, at 45degree angles to the edge of the moat, gets you 4.75m out: from the corner of the moat to the left edge of the bridge, regardless of the thickness of the bridge, assuming that the corners on the left edge of bridge are sitting on land.

the distance we're trying to span is 14.1 or 14.14 (the square root of 200). 14.14 - 4.75 = 9.39. if you lay another 9.5 m bridge over that gap, then you have .11 meters of excess which equates to .055 m on each end (2 inches?). the end that crosses the moat is laying on a corner. you wouldn't want its corners hanging over the edge of the moat, otherwise you'd have a very unsturdy path. since .055 m are laying on land, you wouldn't want it to be any wider than .011 m (hopfully you guys understand triangles. i'm too lazy to draw a diagram). so this army is basically walking on 4-inch wide bridges. watch out for the sharks...

but it works and it's ingenious. laying a third bridge on the outside corner of the moat to the bridge placed diagonally will give you some extra breathing room. rookie showed that in his solution too.

for all those people talking about running and jumping, can you image how much a 30ft bridge weighs? mechanically, there's no way you could have people standing on one end, the other hanging over the gap, and have people trying to run and jump the difference. the puzzle says a wise man came up with a solution, not a guy from Jackass =)