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初中物理第二册第55页有这样一题: “用棉垫子把冰盖起来,冰是化得快些,还是慢些?为什么?”笔者发现学生中有以下几种答法: 一答:用棉垫子把冰盖起来,能防止热空气进入冰里,使冰化得慢些。这个答案,论据很不完整。只说出了盖棉垫子能防热的对流,没有考虑到本问题中防止热传递的另一主要形式——传导。抓了芝麻,丢了西瓜。如果仅仅只是防止对流就能使冰化得慢些的话,那末将冰放到铁箱里,不也可以达到同样目的吗?
In the second volume of the junior high school physics book, page 55, there is such a question: “Is the ice covered with cotton mats. Is the ice faster? Or is it slower? Why?” The author finds that students have the following methods: Covering the ice with a cotton pad prevents hot air from entering the ice and slows it down. This answer, the argument is very incomplete. Only the heat-resistant convection of the covered cotton mat was mentioned, and the other major form of preventing heat transfer in this problem, conduction, was not taken into consideration. Caught sesame and lost watermelon. If merely preventing convection can make ice slower, then putting ice in the iron box can not achieve the same purpose?