【英语时差8,16】了解暖水瓶的工作原理-上（在线收听）

These days kids have styrofoam to keep soup hot. But back in the day, there were thermoses. One of their drawbacks was that since their insides were made of glass they were pretty easily broken when dropped. The popping sound they made when they broke was cool to kids, but then we weren’t the ones who had to buy a new one. A thermos keeps things hot not because it generates heat like a radiator, but because it doesn’t allow heat to escape. What’s the best way to prevent heat from escaping? Insulation. You can wrap the hot thing up in a material that doesn’t conduct heat well. Then the soup won’t be able to cool off easily, because the heat can’t escape into its surroundings.