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Dobby; A Free Standing Bridge
Transcript of Dobby; A Free Standing Bridge
Images from Shutterstock.com Overcoming the Worst For me, my biggest problem to overcome was the making of the bridge in itself. I didn't have the motivation to make a very sturdy bridge but then when I sat down to make a real one, I had to keep in mind that I only had 10 pieces of paper. Also, I am very bad at rolling the paper tightly so I had to focus very hard on that and take my time. Luckily, for this, I did not use power tools. I can't work power tools and it would have been an absolute disaster but wait...why would I need power tools to cut paper? Lets Be Honest I did not use my original design (which yes was mainly based on the example one) but after it failed miserably, Jess helped me figure out how to make everything even and strong. I also didn't make this at home so no...no animals were hurt using this...I got a paper cut does that count? Variables: Solving the Mystery My first bridge crushed under about 50 grams of weight because it was so badly made. I had trouble rolling the circles and every time I went to go tape them they would unravel a bit and I didn't notice until the first bridge crushed. Then I realized that my legs weren't the same length and its very hard to cut those things even. Here Lies Dobby: I weighed the bridge all by itself on a scale!
The hanging weight I weighed on a scale too...
The downward weight I figured out BECAUSE I used the full water bottle which was 3500 g and then added the weight of the 6 books it held.
Acceleration Due To Gravity = 9.8 m/s squared.
Calculations!! Pillar Forces: 36.9g/1=xKg/1000g = .0396Kg
.0369(9.80)= .361 N Down
.361/4(pillars) = .090 N per pillar
Force of Gravity [hanging mass]: 987.1g/1=xKg/1000g = .0987 Kg
.0987(9.8)= .967N Down
Force of Gravity [Top Mass]: Each Book = 2.2 Kg --> 6 books = 13.2 Kg
Bottle Of Water = 3500g
3500g/1=xKg/1000g = 3.5 Kg
3.5Kg +13.2Kg= 16.7 Kg(9.8) = 55.86N Down
Overall Normal Force: .0369 +.0987 + 5.7 = 16.9 (9.8) = 166.3N Down
Crossbar: 166.3/ 2(crossbar) = 83.15 N per crossbar