Author Topic: WoK: Bridge Crews & Bridges  (Read 12360 times)

Inkthinker

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Re: WoK: Bridge Crews & Bridges
« Reply #105 on: September 15, 2010, 11:40:31 PM »
Quote from: Eerongal

I cant honestly see a 30 foot long bridge weighing a mere 2000 pounds able to hold so much weight, however, as established, it cannot possibly weigh more than this for carrying purposes.)

Depends on the materials and how its constructed. I've seen some ridiculously light structures (usually bamboo) hold quite a lot of weight. I'm willing to buy that if the wood is tough and strong and light, then it could work.

Just to throw an additional wrench in the works, Brandon has stated in interviews and such that gravity on Roshar is lower than Earth-normal (0.7 or 0.6, I think?), which does have some effect on all calculations.

I love that you guys are putting this much thought into it. Whether the math works out easily or not, it's fun to see readers get involved to this degree.
« Last Edit: September 15, 2010, 11:43:33 PM by Inkthinker »

Eerongal

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Re: WoK: Bridge Crews & Bridges
« Reply #106 on: September 16, 2010, 12:31:24 AM »
Quote from: Eerongal

I cant honestly see a 30 foot long bridge weighing a mere 2000 pounds able to hold so much weight, however, as established, it cannot possibly weigh more than this for carrying purposes.)

Depends on the materials and how its constructed. I've seen some ridiculously light structures (usually bamboo) hold quite a lot of weight. I'm willing to buy that if the wood is tough and strong and light, then it could work.

Just to throw an additional wrench in the works, Brandon has stated in interviews and such that gravity on Roshar is lower than Earth-normal (0.7 or 0.6, I think?), which does have some effect on all calculations.

I love that you guys are putting this much thought into it. Whether the math works out easily or not, it's fun to see readers get involved to this degree.

Actually, that does throw a significant monkey wrench into the works.

Obviously, weight will be reduce to about 70% of what they were.

Also, objects would fall slower, meaning more time to push the bridges over the edge, obviously requiring less weighting.

With this snippet of info, i see no reason why it wouldnt work, and without weighting at the back, honestly.
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Munin

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Re: WoK: Bridge Crews & Bridges
« Reply #107 on: September 16, 2010, 01:08:20 AM »
The lower gravity would only affect how easy it is to carry, not how hard it is to push across.

The theory is that they're weighting it down themselves, but with low gravity, they weigh less, as well.

At least, that's how I think it works. It's been a few years since I took a physics class.
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rjl

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Re: WoK: Bridge Crews & Bridges
« Reply #108 on: September 16, 2010, 01:14:13 AM »
The lighter gravity matters only if they're pushing it down as opposed to leaning on it to hold it down, as if they're leaning on it, then the lighter gravity means their lean exerts a weaker force as well, also, generally leaning exerts a greater force than pushing.



Bassically for it not to fall the Dwnward force F (exerted by the bridgemen) multiplied by the distance z has to be equal to or greater than the weight of the bridge w multiplied by the distance x, where the distance x is the distance from the middle of the bridge to the edge of the plateau it's being pushed out from.

Let's say that the bridgemen lean on it to put half their weight on it and lets postulate that they weigh about 100 pounds, the bridge weighs 2000 pounds and is 30 foot long and they're trying to push it accross a 25 foot casm.

When the bridge touches the other side they'll have 5 foot of it left, and lets say their downward force is effectively a foot in from the edge meaning they have 4 foot of distance from downward force to edge of casm.

The bridge will currently have it's middle 10 foot out, thereby exerting a moment of 2000 pounds x 10 foot x g (where g is the appropriate gravitational constant) so, 20000g

If we divide 20000g by 4 we get 5000g, that would mean 50 bridge men exerting 100g each to stop it from falling as it reaches the other side.

Maybe they could lean a bit more, three quarters of their weight, 5000g/150g = 33 and a third bridge men, or 34 as we don't have thirds of men lying around.

Not sure how 34 bridge mena re going to crowd around it and manage to lean a third of their weight on the thing...

I'm thinking our casms are probably narrower.

Inkthinker

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Re: WoK: Bridge Crews & Bridges
« Reply #109 on: September 16, 2010, 02:52:09 AM »
Seriously. In light of shorter bridges, the max width should probably be adjusted to 20 feet at most, 15 on average. 25 feet is too long for a 30' bridge (if nothing else, I don't think it would leave enough overlap on either side).

They still need to drop and shove for any gap more than 5-6 feet wide, unless you guys really think having your army constantly trying to long-jump lethal-drop chasms in full kit is a good way to march.

The part that bothers me now is the distance between the crew and the Parshendi shooting at them. From 20 feet away, I don't know how any bridgeman lives through a single charge that isn't fully supported by covering fire.

Munin

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Re: WoK: Bridge Crews & Bridges
« Reply #110 on: September 16, 2010, 03:41:37 AM »
The part that bothers me now is the distance between the crew and the Parshendi shooting at them. From 20 feet away, I don't know how any bridgeman lives through a single charge that isn't fully supported by covering fire.
Maybe the Parshendi have really bad eyesight? Or they're facing the sun?
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Eerongal

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Re: WoK: Bridge Crews & Bridges
« Reply #111 on: September 16, 2010, 05:36:15 AM »
The part that bothers me now is the distance between the crew and the Parshendi shooting at them. From 20 feet away, I don't know how any bridgeman lives through a single charge that isn't fully supported by covering fire.
Maybe the Parshendi have really bad eyesight? Or they're facing the sun?

Nah, they probably have rambo-kinson disease. You know, how the good guy can just stand there and fire away at a huge enemy force and never be hit once?
Example :P
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rjl

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Re: WoK: Bridge Crews & Bridges
« Reply #112 on: September 16, 2010, 11:13:33 AM »
If we go for a 20 foot gap, and have the pushing bridgemen lean with half their weight, when the 30 foot bridge is about to be accross:

5 *2000g = 10000g

10000g / 8 = 1250g

Each bridgeman exerts 100g with his lean, so, rounding it up, 13 bridgemen leaning on it with half their weight. (this is assuming that the effective force of their lean can be taken to be two foot from the edge of the bridge)

goateye

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Re: WoK: Bridge Crews & Bridges
« Reply #113 on: September 16, 2010, 11:23:03 PM »
i found the whole bridge thing boring.  I understand why it is there but bleh.
bridges with kalidin's whining page after page got old.

could just be me....

Munin

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Re: WoK: Bridge Crews & Bridges
« Reply #114 on: September 16, 2010, 11:59:58 PM »
i found the whole bridge thing boring.  I understand why it is there but bleh.
bridges with kalidin's whining page after page got old.

could just be me....
It's just you. Those chapters are some of the best parts of the book, in my opinion.

Especially any lines by Rock.
There's a difference between what's best and what's right. What's best might be different tomorrow or the day after, but right and wrong will stay the same after a thousand years.

goateye

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Re: WoK: Bridge Crews & Bridges
« Reply #115 on: September 17, 2010, 12:24:16 AM »
i found the whole bridge thing boring.  I understand why it is there but bleh.
bridges with kalidin's whining page after page got old.

could just be me....
It's just you. Those chapters are some of the best parts of the book, in my opinion.

Especially any lines by Rock.
Oh yeah Rock did save that part of the book for me.

Ari54

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Re: WoK: Bridge Crews & Bridges
« Reply #116 on: September 17, 2010, 06:15:21 AM »
i found the whole bridge thing boring.  I understand why it is there but bleh.
bridges with kalidin's whining page after page got old.

could just be me....
It's just you. Those chapters are some of the best parts of the book, in my opinion.

Especially any lines by Rock.

They were good once they got going, but to be honest I had more fun with Shallan and Dalinar at first.

Nightfire107

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Re: WoK: Bridge Crews & Bridges
« Reply #117 on: April 07, 2011, 08:12:39 AM »
No, Kalidin's character and story are the best ever IMO.
"We're Bridge Four, we've been around. We've liven in the crem and been used as bait. If it helps you survive, it's good. That's all that needs to be said about it."

Inkthinker

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Re: WoK: Bridge Crews & Bridges
« Reply #118 on: April 07, 2011, 09:17:03 PM »
hahaaaa... I was just looking for this thread the other day, too. The math is useful.  ;D

CabbyHat

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Re: WoK: Bridge Crews & Bridges
« Reply #119 on: April 07, 2011, 09:40:43 PM »
This thread makes me wonder if Jasnah's line about never trying to rediscover something that someone else has worked out for you is a subtle nod to the fandom's tendency to do exactly this...
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