Competition
By the end of the third day of construction, we were left with this:
Where as the other team had constructed this beauty.
As per pre-decided rules, mass would be added to the bridge until it broke. Our team went first with the weight being supported by triangle in the middle.
.........
In the end, our bridge held 2970.9g! In terms of efficiency which is what our competition was about, our bridge, which was 48.7g, held 6186% or its own weight. I was very impressed!
However, then the other team went. Without being too critical, I was not expecting much of their bridge. I had heard of their budget problem. It was 35.8g, had little or no trusses, looked very flimsy. However, it kept going, and held 2690.9g! We were shocked to discover that because of their low mass, they had an efficiency of 7278%!
So they won.
Analysis
Our bridges were then examined afterword. Here was ours:
You may notice that the flaw was in the side support. The bridge twisted itself, broke a single truss, and slipped a few centimeters to its doom. Nothing else, not one material, snapped- it was only the glue. I thought that was a huge success on its own. The forces that this broke down to were that the compression on the top beam (the mini skewers), which moved them sideways. Our bridge was not built for this kind of sideways z-axis force, so it collapsed. Up until then, however, there was very little bend in it, and it held up well.
But there were some big differences that I would like to bring up between the two bridge designs. When weight was added to their design, it bent instantly. It bent more with every single addition of weight as well, and by the end looked like a "u". Ours, however did not, and remained straight until it gave out. I think that that makes ours a better bridge in general, as it resisted the impact of the downward forces more than the other bridge. This made it sturdier, and it even held more. This is all not to mention that it was also way under budget.
So there.
But I guess by the rules, we have to admit they won. Shame is upon my family.
Some Closing Calculations
Just thought it would be interesting to reflect back on some of our calculations. Let's say that we really wanted our bridge to win this little competition, based on efficiency. Now we can't really add much more weight to our bridge without it snapping, unless we rebuilt the entire thing with a better design. However, we can change the second part- the mass of the bridge.
Let's say we just remove some unnecessary components. In our bridge, i would remove the truss on the bottom. By numbers, the eliminates...12 tooth picks, and one piece of a skewer, which I would judge, thickness wise, as about two more toothpicks. In total, 14 tooth picks. With our measurement of one toothpick having a mass of about .5 grams (they are very light) that would eliminate a total of 7 grams from our bridge, bringing our mass to 41.7g. Assuming that that truss had little to no affect on the bridge, we can do a hypothetical re-evaluation. 2970.9g divided by 41.7g and times 100....is.....7124.5%, just 100 percent shy of the other bridge. Hmmm.....
The question now becomes, how much would we have to remove to get past the other team, in terms of efficiency? Simply equation here: 2690.9/35.8 = 2970.9/x, with x coming out to be...39.5g. So we would have had to sacrifice a little less than 10g to equal out to or opponents. An interesting thought.
