8 ms·
Life at Low Reynolds Number (1976) [pdf]
- gtsnexp 5y agoBeautiful illustrations!
- dandare 5y agoSo this sent me down the wikipedia rabbit hole :D One thing I never realised is how dramatically the viscosity of water changes with temperature. This is probably why you can recognise hot water from a cold water in a video. Temperature (C) / Viscosity (mPa*s) 0.01 1.7911 10 1.3059 20 1.0016 25 0.89002 30 0.79722 40 0.65273 50 0.54652 60 0.46603 70 0.40355 80 0.35405 90 0.31417 99.606 0.28275
- steerablesafe 5y agoI had the pleasure to measure that in a university lab, it's very apparent when measuring near 0°C takes roughly 2x longer than on room temp.
- deleted 5y ago[deleted]
- KineticLensman 5y agoI've sometimes thought that the sound of water in my shower changes as the water reaches max temperature. Perhaps that's why?
- ThrustVectoring 5y agoI was always able to tell as a kid in my childhood home, likely plumbing-system dependent.
- pfdietz 5y agoI wonder how pressure affects that, particularly near boiling. EDIT: https://www.nature.com/articles/2151053a0 https://www.nature.com/articles/2151053a0
- HPsquared 5y agoAnother interesting temperature dependence of water is the negative thermal expansion between 0°C and +4°C. The maximum density is at +4°C. Therefore, between 0 and 4°C the usual law of natural convection (heat rises) is inverted and you get "heat falls" instead. What this means is that in winter, the ice on top of water can be frozen but the water can be warmer further down and resist further heat transfer. Natural convection will not act to cool the water from above, and a stable stratified temperature gradient can form. This allows bodies of water to remain liquid in winter for longer than you'd expect in a "normal" liquid.
- pge 5y agoThe author of this paper is Ed Purcell - https://en.wikipedia.org/wiki/Edward_Mills_Purcell https://en.wikipedia.org/wiki/Edward_Mills_Purcell If you studied physics in college, you may have used the textbook he wrote, Electricity & Magnetism.
- mncharity 5y agoHmm, it looks like (TFA author) Purcell's "Back of the Envelope" AmJPhys column, paywalled for decades by AAPT, is currently available online.[1] "a monthly feature [...] from January 1983 through July 1984. Three new "order-of-magnitude" problems were presented each month [...] there were 57 problems, the discussion of which fills something like 150 column-inches". Eg, the ratio of tide influence from Moon and Sun is 7/3, so what is the ratio of their mean density? [1] https://www.aapt.org/Publications/AJP/Readers/back_of_the_envelope.cfm https://www.aapt.org/Publications/AJP/Readers/back_of_the_en...