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 kinetic energy. Kinetic energy means the amount of motion the molecules 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.

以两个钉子和他们一起大力刮。现在触摸的地方，你被刮。它的热！让他们冷静，并再次尝试。它的热了！您可以这样做，整天和指甲永远不会停止增长热点。如果热的液体，它是一个无限量，即使在一个微小的指甲。什么更好的答案吗？热是一种动能的措施。动能手段的运动量在指甲的分子，或有多少，他们对彼此争抢。热勺加热你的手不会因为看不见的东西正在浇筑，但由于勺子快速冲撞分子的分子打在你的手，开始他们过于拥挤。在指甲的情况下，所有的需要产生更多的热量是开始再次冲撞这些分子后，他们已经平静下来。你永远不会用完的热量。