My favourite possessions of the year are:
My head scarf: I got it in Morocco back in February. We were forced to buy them on the way to the Sahara, €10, as far as I recall. It kept my porcelain face safe from the abrasive sand and scouring sun all the way to the tallest dunes in the country.____________________________________________________________________
The hitherto snubbed1 shroud rose to favour when I tired of trying to turtle into the wide brim of my fleece. I wrap it round my neck and jaw-line. Since it is 2.62 m long it goes around a few times.2 Now my neck and chest are safely tucked in.
My gyroscope: I got it as a gift from Cillian and the Mrs. I look forward to coming to grips with the mathematics/physics behind it.3
My netbook: I've had some [self-inflicted] problems the past few months with my desktop, so I spend most of my time with the VGA cable to my 20 inch monitor connected to the little one. That and its mobility got it on the list.
1I've been waiting 12 years to use that phrase appropriately! Another highlight to the year. It is from Nobel Laureate Séamus Heaney's An Advancement of Learning.
2 It goes around 5 and 3.5 times.i
3Pardon the pun, or not. Hell, if you complain about it, I'll just delete your comment!
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iIf I tie it really tight around my head it is the former, if I take care to keep it loose, it is the latter. I took out the measuring tape and found that the circumference (C) of my neck is 39cm, a tight wrap is 53cm and loose wrap is 69cm.
I went nuts and assumed that my neck and scarf were cylindrical, so I could calculate the volume ( V=HC/4π) of each of the cylinders, taking 15cm as the neck height. There is about 4 times more air in the loose wrapping. w00t!
iiIts density is 0.01% of liquid water and it follows that eventhough its heat capacity per unit mass is about 25% of that of water, its heat capacity per unit volume is about 0.0015% that of water. If its temperature has the potential to change so easily, why can I barely feel my radiator‽ iii
iii "Thanks for asking, Máirtín..." When objects are heated their density changes. In the simplest case, the heat source is on the ground, i.e. the lowest position in the accerating reference frame.iv The fluid heats, gets less dense compared to the fluid overhead and experiences a buoyancy force, and convection ensues. A critical Rayleigh Number marks the transition from conductive to convection dominant heat transfer. Bluntly, compared to water, Air does not have much going on.v
ivWithout an applied force objects, don't do much. Kinda like drunk people and cattle prods.
vI got the air expansion coefficient and kinematic viscosity here. For water I got them here. The diffusivities took some tracking down. I decided that the diffusivity of oxygen in air would suffice for air and water's turned up after some googling. As far as the temperatures go... I picked what my radiator felt like and what my room feels like, respectively.
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Some interesting links that cropped up while I was sifting through the calculations to put in the post:
Rood, E.S. "Thermal Conductivity of Some Wearing Materials", Physics Review Letters, pp 356-361 Vol. 18, 1921. Damn her units. In the abstract she has a mismatch of SI units and neglects to list the pertinent units of the conductivity.
These guys had lots of indepth stuff on the properties of cotton, Air permeability, Weight per unit area, and Thermal conductivity. α
This guy did a great job on calculating the condesnation temperature for one's breath.
This lady composed a Matlab program for calculating the Schmidt Number of binary gas mixtures
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αThey had it as: 53 W/m/K. I was rather sceptical of that. I suppose my scepticism is rooted in associating cloths with insulators. They are probably good insulators because of all the air in them... Nonethless I stand doubtful.
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