Post B58oZtyjQ8e67xpuE4 by dlakelan@mastodon.sdf.org
 (DIR) More posts by dlakelan@mastodon.sdf.org
 (DIR) Post #B58oZtyjQ8e67xpuE4 by dlakelan@mastodon.sdf.org
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       Today was a good day. A tiny bit of #anarchist university happened. Specifically my older son has this personal project due for IB 10th grade, and his project is to investigate how climbing chalk benefits rock climbers. So we've got this little apparatus to investigate the friction properties of little patches of leather on a sandstone flagstone from the front yard. before the CO evacuation on Sunday we did the first set of experiments.
       
 (DIR) Post #B58oZuF2RVgowXSvdw by dlakelan@mastodon.sdf.org
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       He weighed the leather down with a couple of 3/4 inch chrome steel nuts (thats what she said) in a paint cup, then added weights to the other cup attached to the other end of a string dangling over a pulley. then added small 1/4 inch nuts until it weighed down enough it falls to the floor. we did this dry, and then dry and with chalk. Today we continued, we did a second piece of leather, dry, then wet, then wet and with chalk.
       
 (DIR) Post #B58oZuUHWpsnhob6P2 by dlakelan@mastodon.sdf.org
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       The great thing about this is that his intuition was that chalk should increase friction, but absolutely it doesn't so far, it seems to reduce it.Also adding water created a much stickier situation. So right away we are faced with reality destroying our simple models.This experiment is absolutely doable as an undergraduate lab, and we are using Quarto and Julia to write text, analyze the data, and make graphs. I'm going to have him load the raw data into a SQLite file and write queries.
       
 (DIR) Post #B58oZujWcA4mT5jHA8 by dlakelan@mastodon.sdf.org
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       Next I had my wife find a paper we could have him read, to see how science papers look. She chose one we wrote together about analysis of cartilage in ear microtia (developmentally defective ear formation). Its like 5 pages so short and readable without specialized biology knowledge. Tomorrow hes supposed to read that and start writing up the reaults of our stuff so far.We could totally do this as a video and have it be a lab people could do at home for like $50 worth of stuff.
       
 (DIR) Post #B58oZuz7gAYLFT1jTU by dlakelan@mastodon.sdf.org
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       Low tech equipment is kind of a specialty of mine. you can do a lot of great experiments without too much requirements. Friction, vibrations, heating, cooling, etc. minimal requirements maximal combined educational opportunities.
       
 (DIR) Post #B58oZvASzzcvoeKn9k by azonenberg@ioc.exchange
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       @dlakelan Hypothesis: the chalk is not there to increase friction of a soaking wet surface, it's there to act as a desiccant. It's only effective if there's enough chalk to soak up a little bit of sweat and still be broadly dry and powdery.So you're not comparing chalk-water slurry vs soaking wet surface, you're comparing slightly moist surface to slightly moist chalk.
       
 (DIR) Post #B58oewbr49KFjeXYWW by azonenberg@ioc.exchange
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       @dlakelan it would not surprise me if there was a tipping point beyond which the chalk got saturated and was no longer effective at increasing friction, and perhaps even made things worse. Finding and graphing that point would be an interesting experiment
       
 (DIR) Post #B58olMyzvKK3GgQequ by azonenberg@ioc.exchange
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       @dlakelan The hardest part would likely be figuring out how to moisten the surface by a very slight and controllable/repeatable amount
       
 (DIR) Post #B58zIfiAJNDiS34ecS by marjolica@social.linux.pizza
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       @azonenberg @dlakelan apply steam ( in a time and distance contolled way) from a kettle? To restore dryness use a hair dryer?
       
 (DIR) Post #B59XpMaloXzN9TNKAC by dlakelan@mastodon.sdf.org
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       @azonenbergWe had the same theory. we used a single spray from a spray bottle set to mist, from about 2 feet away, distilled water, and then added chalk to the surface afterwards.The interesting thing was this slight bit of water notably **increased** the friction, and adding chalk notably decreased it back down to below the level of dry leather.chalk decreased friction in every experiment we ran. great stuff! my son is challenged now to think about this very deeply.
       
 (DIR) Post #B59ZAJS4mhunRprV8i by azonenberg@ioc.exchange
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       @dlakelan Interesting. Maybe leather is just not a good simulant for human fingers in this regard?
       
 (DIR) Post #B59ZibUOEEzvEfIMuO by dlakelan@mastodon.sdf.org
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       @azonenbergThat is definitely a hypothesis we have discussed. We also think probably we should turn the leather over and do the smooth side, except because of institutional issues he has a very short timeline to complete a 15 page paper on this topic so we are trying to balance experiment time, writeup time, and data analysis time. he plans to follow up after the report with further experiments as part of the Friday afternoon science club (sponsored by Caltech).