A thermos flask keeps cold water cold and warm water warm , but how does it know which is cold and which is warm ?????
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SW-User
No one knows. Research into the modern flask has brought new questions about their almost magical abilities to keep stuff cold or hot. Many think it's a hoax and people just say stuff is cold or hot when it's really just lukewarm at best..
· Reply · Translate · Nov 12, 2023 · Edited: 1 yr ago 
