5 ms·
Can someone explain why Newton's Law of Cooling isn't a sufficient explanation? The temperature delta is clearly larger with hot water, do one would expect it t
by fny 4y ago
Can someone explain why Newton's Law of Cooling isn't a sufficient explanation? The temperature delta is clearly larger with hot water, do one would expect it to cool faster, no?
- epgui 4y agoYes, it cools faster at t=0, but it will take longer to cool down.
- happyopossum 4y agoCooling faster and reaching sub zero temperatures faster are two different things. The hotter water will drop more degrees per minute/hour based on Newton, but at some point the two liquids will be the same temperature, and then you’re assigning some sort of thermal momentum that Newton doesn’t cover.
- ddingus 4y agoWould the warmer water not have currents present from convection? Those are a source of inertia. There is a case for the warmer liquid never actually reaching the same state the cooler liquid is in.
- saeranv 4y agoOther people have answered, but I think this is slightly more intuitive way to put it: Newton's law of cooling states that the rate of temperature reduction (heat loss) of a body is proportional to the temperature delta between it and its ambient surroundings. We can write this as: dT/dt = kT Where T is temperature delta, t is time, and k is some proportionality constant. So the rate of cooling is changing as the delta temperature reduces, specifically, it is getting exponentially reducing as it gets closer to thermodynamic equilibrium (where no heat is exchanged): T(t) = Ce^kt C = T(0) Which means there is a larger cool down with the hot water at first, but under this simple model, once the T(t) hits the same temperature of the cool water it's being compared to, it's cooling rate should be equivalent (and a lot slower).
- fny 4y agoThis should have been obvious.
- andrewchambers 4y agoHot water would need to first reach the temperature of the cold water (and overtake it) before freezing... Your explanation doesn't make sense.