🔁 能量转化：从一种变成另一种🔁 Energy Conversion: One Form Becomes Another
上一片里，动能和势能此消彼长，机械能的总量一动也不动。这一片把镜头拉远：能量的“变身”，远不止这两副面孔。Last leaf, kinetic and potential energy traded places while the mechanical total held still. This leaf zooms out: energy has far more costumes than those two.
第 1 步：烧掉的是油，跑起来的是车Step 1: Burn gasoline, move a car
先看最熟悉的一幕：汽车为什么加满油就能跑？Start with the most familiar scene: why does a full tank make a car go?
汽油里存着化学能，点燃后释放出来，推动发动机，最后变成车轮转动的动能。能量并没有“被用光”，它只是从化学能变成了动能（还有一部分变成了热能溜走）。小火箭给这条链画了重点：化学能 → 动能，每一环都在传递同一份能量。Gasoline stores chemical energy. Ignite it and the energy is released, drives the engine, and finally becomes the kinetic energy of spinning wheels. The energy isn't “used up” — it merely changed from chemical to kinetic (with a share slipping away as heat). The little rocket underlines this chain: chemical → kinetic. Every link carries the very same energy.
汽油之外，能量还会穿什么“衣服”？看看桌上的台灯。Beyond gasoline, what else does energy wear? Look at the desk lamp.
第 2 步：灯点亮时，能量在做什么？Step 2: What does energy do when a lamp glows?
电线把电能送进灯泡，灯丝一亮：一部分变成看得见的光能，一部分变成摸得到的热能——所以灯泡用久了会发烫。一条链可以分岔：电能 → 光能 + 热能。转化的路上能量从不消失，只是一边走路，一边换装。The cord delivers electrical energy to the bulb; the filament glows. Part becomes visible light energy, part becomes heat you can feel — that's why a lamp gets warm. A chain may branch: electrical → light + heat. Along every conversion the energy never vanishes; it walks on and changes outfit as it goes.
那汽油里的化学能、电池里的电能，最初又是从哪来的？So where did the gasoline's chemical energy, and the battery's electrical energy, come from in the first place?
第 3 步：追到源头：太阳Step 3: Follow the chain to the Sun
植物用光合作用，把阳光的光能变成养料里的化学能——花长大、结果实，能量都存进了身体里。煤、石油、食物里的化学能，追根溯源几乎都来自太阳的光能。光能 → 化学能，这条链把太阳和我们的每一天接在了一起。Through photosynthesis, plants turn sunlight's light energy into the chemical energy of their food — as a flower grows and fruits ripen, the energy is stored inside. Follow the chemical energy in coal, oil and food far enough back, and almost all of it leads to the Sun. Light → chemical: this chain links the Sun to our everyday lives.
🎮 你来当能量侦探（30 秒）🎮 Your turn: energy detective (30 seconds)
道理讲完了。左边 4 个场景、右边 4 条能量链——点一个场景，再点它的链，全部接上就通关。Theory done. Four scenes on the left, four energy chains on the right — click a scene, then its chain, and connect them all.
一句话记住它：能量不会消失，只会不断变身——顺着链条找，它总是从一种能量变成另一种，总量始终不变。Remember it in one line: energy never disappears — it keeps changing form. Follow the chain and you'll always find it moving from one kind to another, with the total unchanged.
汽车：化学能 → 动能；台灯：电能 → 光能 + 热能Car: chemical → kinetic; lamp: electrical → light + heat光合作用：光能 → 化学能；食物、煤、石油的化学能大多来自阳光Photosynthesis: light → chemical; the chemical energy in food, coal and oil mostly comes from sunlight每个场景都是一串转换链，能量在转化中总量不变Every scene is a chain of conversions — and the total energy stays the same
内容参考 OpenStax 等公开教材，多来源核对 · AI 生成、人工审核 · 发现错误欢迎指正，帮这片叶子长得更好。Based on OpenStax and other open textbooks, cross-checked across sources · AI-generated, human-reviewed · Spotted a mistake? Tell us — help this leaf grow.
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