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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.
以兩個釘子和他們一起大力刮。現在觸摸的地方，你被刮。它的熱！讓他們冷靜，并再次嘗試。它的熱了！您可以這樣做，整天和指甲永遠不會停止增長熱點。如果熱的液體，它是一個無限量，即使在一個微小的指甲。什么更好的答案嗎？熱是一種動能的措施。動能手段的運動量在指甲的分子，或有多少，他們對彼此爭搶。熱勺加熱你的手不會因為看不見的東西正在澆筑，但由于勺子快速沖撞分子的分子打在你的手，開始他們過于擁擠。在指甲的情況下，所有的需要產生更多的熱量是開始再次沖撞這些分子后，他們已經平靜下來。你永遠不會用完的熱量。
