Need help with impossible Bridge Project! Desperate.

[pocobueno1388]

Okay, I am in Physics...and I have this bridge project due this week on Thursday  :-\ I have honestly built 3 different bridges, and they all failed. I am to the point of being really stressed out, so I need your guys HELP badly. I will type out exactly what my sheet of paper says explaining the project, and maybe one of you are smart and can help me come up with a design that will work? -prays-

<b>1.)</b> Bridge must be of one single unit construction.
<b>2.)</b> A one-inch cube must be able to pass under the bridge through the longest part parallel to one side of the bridge with one book on the bridge (each book weighs around 2 pounds). You may only use a ruler to push the cube under the bridge. When loaded with weight, the bridge must not touch any part of the floor.
<b>3.)</b> The brdige must be constructed of only ONE sheet of paper
<b>4.)</b> The bridge must have a mass NOT to exceed 10 grams. 50 points deducted from grade for ever gram above 10 grams.
<b>5.)</b> Only glue will be allowed to hold the bridge together (any kind)
<b>6.)</b> Bridge supports must only be made of glue and the paper. Glue sticks in their solid form are not allowed.
<b>7.)</b> Grade is based on the number of text books (7 1/2" x 91/2") supported by bridge freestanding for ten seconds.
<b>8.)</b> 3 points awarded for every textbook supported.

You have no idea how much I will appreciate any help I can get, thank you very much  :)

[AndyB]

http://www.google.ca/search?hl=en&q=paper+bridges&btnG=Google+Search&meta=

[pocobueno1388]

I've tried that, and it doesn't help me. Any other ideas?

[AndyB]

If that was [b]no help at all[/b] (all those links), maybe you want to find a structural engineering student and trade them beer for ideas.  Alternatively, look at arched structures and think about lamination as a means of strengthening your materials of construction.

[pocobueno1388]

I can not use lamination, glue only. I thought about laminating with glue...like dipping parts, BUT...it then makes the bridge go over 10 grams of weight. So, I am pretty much stuck. I am just wondering if anyone can think of a way to use just one piece of paper to build a simple bridge to support a lot of weight using glue only. Because I can't think of anything :/ all of my ideas call for more paper then I have to use.

[ober]

When we're talking about paper... what kind of paper are we talking about?

I had an assignment in high school where we had to use nothing but a manila folder to hold a large amount of weight.  The only adhesive was glue.

My idea was a simple cone (weight distributed downward and evenly across the entire structure).  Keep in mind that the best and strongest structures are made of triangles, cones (or tapered cylinders), and arches.  With that knowledge alone, you should be able to come up with something that will withstand at least a few textbooks if you're even half decent as a structural engineering student.

[AndyB]

So far - without any beer - I can use a single standard sheet of paper, no glue, and make an arched structure that holds up three golf balls (whatever they weigh) and roll a golf ball under it.  If I had glue I could make it stronger.  Make one, see how it flexes then bend/crimp the paper to resist the bending forces.  The 'trick' is that the ends of the paper need to meet (i.e. a closed loop) so one side of the arch resists forces from the other and vice versa.  It's all about understanding structures.

[.josh]

nono, it's all about understanding the nature of the paper.  just lay the paper flat across as a bridge.  do not think of it as the paper bending, for that is impossible.  think of it as everything else bending around the paper.  you can put 100lbs of books on it, and the paper is not moving, rather the space around the paper.  Your eyes are just fooled into thinking the paper is bending because even light bends around it. 

problem solved.  A++ in my book.

[Barand]

You've stopped taking your medication again, haven't you?