eli5: Why can hydro flasks (and all other thermoses) keep liquids cold for longer than they can keep them hot?
In: Other
Heat loss is directly proportional to the temperature difference between the two substances/objects. If you’re trying to keep a mug of iced coffee cold, it’s probably somewhere around 2-8C (refrigerator temperature). Assuming room temperature around 25C, that makes for a temperature difference of about 20C.
If you were trying to keep a mug of coffee hot, it would be somewhere in the range of 70-80C. Again comparing to the room temperature of 25C, the temperature difference is about 50C, over twice that of the cold beverage. So the hot coffee will cool down much faster than the cold beverage would warm up.
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