This week’s article is titled “The ancient art of laying rope” by Bohr and Olsen (2011).
I started this article by reading the abstract, and was immediately intrigued with how ropes are described as helical structures featuring a maximum number of twists. These twists are a geometrical feature as opposed to a material property. When placed under strain, ropes become a zero twist structure and therefore do not rotate in either direction.
STOP - My mind immediately pictured DNA in its helical form. I imagined a side by side comparison of rope and DNA and I wondered if their structures would appear similar to one another. I wondered if DNA would also become a “zero twist structure” when placed under strain. What more can we learn about DNA by studying ropes? How many twists does it take to create a zero twist structure?
It turns out that I’m not the only one to make a connection between ropes and DNA. DNA actually represents an optimal helical structure, in which the twists are as closely packed as can be due to the molecular geometry.
To create the optimal rope structure, a rope layer must consider the following: the number of strands, the rotation of the strands, and tensile stress. To achieve the zero twist configuration, the strands must maximally rotate in one direction, while the rope is maximally twisted in the opposite direction. This also accounts for the rope's ability to maintain a constant length, as it is in essence, in equilibrium.
STOP - There was a lot of math presented within the paper to explain how the author’s arrived at these conclusions. It was way over my head. It seemed to involve a lot of trigonometry which I found interesting. I have very little experience with trigonometry, but it was all in regards to triangles and determining missing angles etc. Ropes are helical, and obviously not triangular, so how are they connected?
Activity
I chose to try the flat braiding activity this week. I attempted to do the activity with 5 pipe cleaners, and it was a bit of a mess. The pattern started out okay, but I struggled to maintain it for more than a few turns. I think part of the issue was that pipe cleaners are essentially just a metal wire encased in fuzz. They don’t lay flat on top of each other in the same way as ribbon or paper. It was fun to create a product again, even if it didn’t turn out pretty. I used to do the odd craft when I had more time, but I stopped when I started this program as I was just way too busy for a hobby. I forgot how much satisfaction there was in watching the end result appear.
Very interesting. The mathematics of rope is still a bit above my head but I like the idea that there is math in pretty much everything.
ReplyDeleteI know what you mean about putting things aside when things get busy. The course activities have been a nice push and reminder to make and do which can be very relaxing.
You should try cordage with raffia. It's probably more pliable than pipe cleaners.
The connection between rope and DNA is very interesting. This left me wondering if there is an application in which this idea of twisting rope could be used in high school science when students are learning about DNA and its structure.
ReplyDeleteSimilar to your experience, I also found the material that I used to try my activity was not ideal. It would be interesting to try the same activity again using different materials to see which works the best.