Recent comments in /f/askscience
bella_68 t1_j5s8tpz wrote
Reply to comment by Lampshader in Why does hot air cool? by AspGuy25
Idk how hot a car gets when sitting in the sun but it was hot enough to melt the glue on the electrical tape covering my steering wheel. Interestingly, the glue was liquid and the liquid was everywhere but the tape was still on the steering wheel because the way it was wrapped and the fact that the glue was also still there to some extent.
Unfortunately for me, I get a rash anytime I touch glue
AStrangerSaysHi t1_j5s2n5u wrote
Reply to comment by CrustalTrudger in Can sedimentary rock for on land? by 24_Elsinore
I don't know why reading this answer triggered a childhood memory for me, but: as a kid, I used to love loess... rocks? stones? collections? deposits? clumps?... and would collect bits of it whenever we visited eastern Georgia on vacations (I'm from the dueling banjos part of Georgia for reference). I remember loving the texture of those little bits.
[deleted] t1_j5s2fc5 wrote
Reply to comment by mathologies in What are the forces on Earth’s Inner Core that change its speed? by BayRunner
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zebediah49 t1_j5s0zx3 wrote
Reply to comment by Denamic in Why does hot air cool? by AspGuy25
The relevant point is that visible light will happily go through a normal glass window, whereas long-IR will not. Windows are opaque (and pretty reflective) to thermal cameras.
Clarknt67 t1_j5s09as wrote
Reply to comment by Cobra800089 in What are the forces on Earth’s Inner Core that change its speed? by BayRunner
I agree. I don’t think the magnetic field is definitively understood. Oddly. Since it’s all around us.
[deleted] t1_j5s08ya wrote
Reply to comment by Lampshader in Why does hot air cool? by AspGuy25
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Lampshader t1_j5rzle5 wrote
Reply to comment by dr_reverend in Why does hot air cool? by AspGuy25
The FLIR sales rep recommended black electrical tape when I asked about this.
I dunno what its melting point is but 98% of electronics workbenches will have it within arm's reach already so it's got that going for it
thereisafrx t1_j5rz7fz wrote
Reply to If I had two cups of water, one normal size and one as big as a swimming pool and stirred them both with proportionally sized spoons, would the larger pool of water keep spiraling longer than the smaller? by r3volc
Think about it this way, if you put a quarter on a small hill and rolled it down the hill, and a large stone disk on a proportionally-larger hill, would the large stone disk roll for longer?
Same for the two cases of the fluids in large/small containers, except with the solids there are no viscous forces to consider.
junegoesaround5689 t1_j5rypyu wrote
Reply to why do we not see the reappearance of extinct lifeforms anymore if evolution can retrace its step to redevelop it? by 0011000l
Evolution doesn’t (and can’t) "retrace its steps". So, almost certainly this would be impossible. It would be like two different rainstorms producing exactly the same raindrops falling in exactly the same places with identical lightening and thunderclaps. Waaaay too many variables for the exact thing to happen twice. Similar (ref convergent evolution), yeah, but not identical.
PineappleLemur t1_j5rx08g wrote
Reply to Why does hot air cool? by AspGuy25
Thermal cameras see IR, metals, especially bare metals have a really low emissivity, meaning that they radiate very little IR and reflect the rest. (what the camera sees)
Think of it as a mirror, aluminum foil for example has emissivity of under 0.1 (it's a scale of 0-1, 1 being 100% radiating/absorbing) so only 10% of the total possible energy is being radiated and 90% are being reflected.
What you're seeing is a combination of the reflected IR + the radiated IR.
So the surface reflected is likely what you're seeing + the housing.
Take an aluminum foil and literal look at yourself with the camera. Foil is basically a mirror for IR as a glass mirror is for white light (what we see)
Emissivity is affected by material/color/surface. To get a better reading you want to paint it with a black body color, something black with a rough surface and very little visible shine (matte black)
[deleted] t1_j5ruw1k wrote
Reply to Can sedimentary rock for on land? by 24_Elsinore
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[deleted] t1_j5rua9q wrote
VulfSki t1_j5rqk0a wrote
Reply to comment by Glasnerven in Why does hot air cool? by AspGuy25
Yes, I understand how all that functions. Humans get cooked down from perspiration, which is because the energy to evaporate sweat is partially comes form the heat on our body, and air flow helps with that.
But airflow itself doesn't equal cooking in the general sense, because it only works if you are removing heat by taking it to something that is at a lower temperature, can't violate newton's law of cooling.
You did provide a great explanation, even though I was already aware of all that.
[deleted] t1_j5rq1q4 wrote
Reply to comment by chillaxinbball in Why does hot air cool? by AspGuy25
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Denamic t1_j5rocnx wrote
Reply to comment by SXTY82 in Why does hot air cool? by AspGuy25
Thermal cameras use IR. IR, being light, bounces off reflective surfaces.
[deleted] t1_j5rni0v wrote
Reply to Why does hot air cool? by AspGuy25
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[deleted] t1_j5rn1u2 wrote
Reply to comment by Appaulingly in Why does hot air cool? by AspGuy25
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[deleted] t1_j5rmk2f wrote
Reply to comment by CrustalTrudger in Can sedimentary rock for on land? by 24_Elsinore
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[deleted] t1_j5s9o2p wrote
Reply to Why does hot air cool? by AspGuy25
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