⛰️ 重力势能：举得越高，存得越多⛰️ Gravitational Potential Energy: Lift It Higher, Store More
上一片里，动起来的物体带着动能。那还没动、只是被举高的东西呢？小火箭把升降台升起来，积木一动不动，能量却已经悄悄存进去了。Last leaf, moving things carried kinetic energy. But what about something lifted up and standing still? The rocket raises its lift platform — the block never moves, yet energy quietly piles up inside.
第 1 步：举高 = 存能量Step 1: Lifting = storing
小火箭最先想到的是水：高处的水什么都没做，却随时能干活。The rocket thinks of water first: high water does nothing, yet it can work any time.
水坝把水拦在高处。水位越高，水冲下来带动的发电机就越有劲。小火箭把积木吊高，积木一动不动，也存下了一笔能量——它叫重力势能（Gravitational Potential Energy）。举得越高，存的越多。A dam holds water up high. The higher the water level, the harder it drives the generators below. Same with the rocket's lift: hoist a still block upward and it quietly banks a kind of energy — gravitational potential energy. Lift it higher, store more.
那这笔能量到底存了多少？三样东西说了算。So how much energy gets banked? Three things decide.
第 2 步：m、g、h 三个裁判Step 2: three judges — m, g and h
同一颗球，放低层能量小，放高层能量大——高度 h 是关键。公式 Ep = mgh：质量 m 越大、高度 h 越大，势能就越大；g 是地球的重力加速度，约 9.8 米/秒²。高度从哪儿量？先约定一个“零势能参考面”：相对地面，书架顶层有 1.5 米；相对桌面，也许只剩 0.5 米。参考面一换，数值就变——势能是相对的。The same ball on a low shelf stores little; on the top shelf it stores a lot — height h is the key. The formula Ep = mgh: more mass m and more height h mean more energy; g is Earth's gravitational acceleration, about 9.8 m/s². Measured from where? First agree on a “zero-potential reference”: the top shelf is 1.5 m above the floor, but only 0.5 m above the desk. Change the reference and the number changes — potential energy is relative.
存下来的势能，最后会变成什么？And what does the stored energy become in the end?
第 3 步：存进去，冲下来Step 3: stored up, then let go
跳台滑雪选手站在最高处，势能拉满。沿坡下滑，高度一点点减少，势能一点点转成动能。到达起跳台时，存下的能量几乎全变成了速度。水坝发电、滑坡下滑、吊灯坠落，都是同一个套路：先举高存货，再放下来花掉。A ski jumper stands at the very top, potential energy maxed out. Gliding down, the height shrinks step by step and the potential energy turns into kinetic energy. At the take-off it is almost purely speed. Dams, landslides, falling chandeliers — same trick: hoist to bank it, drop to spend it.
🎮 你来开升降台（30 秒）🎮 Your turn: work the lift (30 seconds)
拖质量、拖高度，看势能条实时涨落；再完成 4 个任务，把能量调到目标值。Drag mass and height to watch the energy bar in real time, then hit 4 target energies.
一句话记住它：重力势能 = 被举高攒下的能量，Ep = mgh；同样一笔能量，可以用“小质量 × 高位置”，也可以用“大质量 × 低位置”存出来。Remember it in one line: gravitational potential energy is what being lifted banks up, Ep = mgh — and the same amount can come from “small mass × great height” or “big mass × low height”.
Ep = mgh：质量越大、高度越高，重力势能越大Ep = mgh: more mass or more height means more potential energy高度要相对“零势能参考面”来量，参考面一换，数值就变Height is measured from a chosen zero-potential reference; change it and the number changes存下的势能随时能变回动能：下坡、落水、跳台滑雪都在花这笔钱Stored potential energy turns back into kinetic energy on any downhill, waterfall or ski jump
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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