Question

Explain the thermodynamics of vacuum flask. Please don't just copy and paste from wikipedia, I've read it, but need a simpler explaination.

Answer 1

A thermos flask or a vacuum flask is used to keep a hot liquid hot and a cold liquid cold for a long time, by preventing the loss or gain of heat energy due to conduction, convection and radiation.
The thermos flask consists of a double-walled glass vessel resting on a cork inside a metal or plastic case. The outer surface of its inner wall and the inner surface of its outer wall are silvered. This prevents heat transfer due to radiation. The space between the two walls is almost vacuum and the walls are sealed at the top. The double-walled glass vessel and vacuum prevents heat loss by conduction. The insulating stopper or cork at the top minimises heat loss by convection.

Vacuum flasks are used at home, and in laboratories and industries to store liquids that become gases at low temperatures.