【英语时差8,16】热量动能

 Take two nails and scrape them together vigorously. Now touch the place you were scraping. It’s hot! Let them cool and try it again. It’s hot again! You could do this all day and the nails would never stop growing hot. If heat were a liquid, there would have to be an infinite amount of it even in a tiny nail. What’s the better answer? Heat is a measure of kinetic¹ energy. Kinetic energy means the amount of motion the molecules² in the nail have, or how much they jostle against each other. The hot spoon heats your hand not because something invisible is being poured in, but because the fast-jostling molecules of the spoon hit the molecules in your hand and start them jostling too. In the case of the nails, all that’s needed to produce more heat is to start jostling those molecules again after they’ve calmed down. You won’t ever run out of heat.

1 kinetic   

adj.运动的；动力学的

参考例句：

• There exist many sources of energy both potential and kinetic.存在着许多势能和动能的能源。
• The kinetic theory of gases is the best known example.气体动力学理论就是最有名的例子。

2 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。