Under some conditions can initially hotter water freeze faster than initially cooler water placed in the same freezer?
#thermodynamics
Post a problemLiquid nitrogen is around -196 C, yet a small splash on bare skin often causes no injury at all: what protects the skin, and when does that protection fail?
Why does a droplet of water dropped onto a very hot skillet (well above boiling point) form a levitating bead that skitters around for a surprisingly long time instead of flattening and evaporating immediately?
Why does burning firewood make crackling, popping, and hissing sounds, and why is the noise so much louder and more frequent with some pieces of wood than others?
What actually makes the vanes of a Crookes radiometer (the light-mill in a partial vacuum) spin when light shines on it, given that Crookes's original light-pressure explanation predicted the wrong direction?
What is the physical nature of the glass transition — why does a liquid cooled fast enough become a rigid amorphous solid with a huge (often 10+ orders of magnitude) slowdown in molecular motion, without any obvious change in structure or a sharp thermodynamic phase transition?
Why do physical processes in our universe overwhelmingly run in one time direction (entropy increasing), even though the fundamental microscopic laws of physics are very nearly symmetric under time reversal?
In a partially evacuated glass bulb, a four-vaned wheel with one blackened and one silvered face per vane spins when light shines on it, but it spins with the black faces trailing, not leading as simple radiation-pressure reasoning predicts: why?
Given the air temperature and a pond's depth, roughly how long will it take for the pond to freeze solid from the surface down, and what physical law governs how the ice thickness grows with time?
Can a block of 'ice' actually catch fire and burn, and can a lump of ordinary tin be made to melt just by dropping it into boiling water?
Is it possible for a physical system to have negative heat capacity — that is, to actually cool down when energy is added to it, or heat up when energy is removed?
Boiling crisis / critical heat flux
Research level
What sets the maximum heat flux a boiling liquid can carry away before the surface suddenly overheats and burns out (the boiling crisis), a limit engineers have used empirically for decades?
Under some conditions, does a container of initially hot water actually freeze to ice sooner than an otherwise identical container of initially cooler water, and if so, why?