Eli5: Why can a thermal flask keep items cold for 24 hours, but only hot for 12 hours.

Question

Eli5: Why can a thermal flask keep items cold for 24 hours, but only hot for 12 hours.

In: Physics

Answer 1

There are two factors here.

1. The temperature difference between hot drinks and the outside could be lower than the temperature difference between a cold drink and the outside.
2. Cold drinks often have ice in them. Ice functions as a ‘cold reservoir’. As long as there is a little ice, the drink will stay close to the freezing point of water. When combined with thermal insulation, ice is exceptionally good at keeping your drink the perfect temperature.