摇匀的油醋汁放一会儿又分层，物理上能不能让它一直不分层？
Oil-and-vinegar dressing separates again after shaking — can physics keep it mixed forever?
油醋汁是油（低密度、疏水）分散在水/醋（高密度）中的临时乳浊液。摇匀后液滴靠表面张力暂时悬浮，但油水密度差和界面能趋向最低，液滴会聚并上浮，按斯托克斯定律沉降分层——这是热力学上更稳定的状态。要让它“永远”不分层，需要乳化剂（如芥末、蛋黄/卵磷脂、阿拉伯胶）降低界面张力并形成稳定薄膜；严格地说，物理上无法让互不相溶的两相在纯力学作用下永久均匀混合。
An oil-and-vinegar dressing is a temporary emulsion of oil (low-density, hydrophobic) droplets in water/vinegar. Shaking disperses them, but the density difference and interfacial energy drive droplets to coalesce and rise, separating by Stokes settling—a thermodynamically more stable state. To keep it mixed you need an emulsifier (mustard, egg yolk/lecithin, gum arabic) that lowers interfacial tension and stabilizes a film around droplets, which prolongs but does not make it permanent. Strictly, physics cannot keep two immiscible phases uniformly mixed forever without such stabilization.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#乳浊液 #斯托克斯沉降 #界面
为什么高压锅能比普通锅更快把食物煮熟？
Why can a pressure cooker cook food faster than an ordinary pot?
高压锅密封性好，内部蒸汽无法逸出，气压升高使水的沸点提高到100度以上。更高的温度让食物熟得更快，也更省能源。
A pressure cooker is well sealed, so trapped steam raises the internal pressure and pushes the boiling point of water above 100 degrees Celsius. The higher temperature cooks food faster and uses less energy.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Paul Hewitt,《Conceptual Physics》Pearson 多版
Paul G. Hewitt, Conceptual Physics, Pearson, various editions
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL1930743W：Conceptual physics（按标题+
#气压 #沸点 #厨房物理
为什么在海拔很高的地方煮鸡蛋更难煮熟？
Why is it harder to boil an egg properly at high altitude?
海拔越高大气压越低，水的沸点随之下降，可能只有90度左右。温度不够高，蛋白质凝固变慢，鸡蛋就需要更长时间才能熟。
At high altitude the atmospheric pressure is lower, so water boils at a lower temperature, sometimes around 90 degrees Celsius. With less heat, the proteins coagulate more slowly and the egg takes longer to cook.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Paul Hewitt,《Conceptual Physics》Pearson 多版
Paul G. Hewitt, Conceptual Physics, Pearson, various editions
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL1930743W：Conceptual physics（按标题+
#气压 #沸点 #海拔
为什么用嘴吹一吹热汤，它就凉得更快？
Why does blowing on hot soup make it cool faster?
吹气加快了汤表面的空气流动，带走刚蒸发出来的水蒸气，并促进对流散热。同时加速蒸发，而蒸发会带走热量，所以汤凉得更快。
Blowing increases air flow over the surface, carrying away the just-evaporated vapor and enhancing convective cooling. It also speeds up evaporation, which removes heat, so the soup cools faster.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Paul Hewitt,《Conceptual Physics》Pearson 多版
Paul G. Hewitt, Conceptual Physics, Pearson, various editions
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL1930743W：Conceptual physics（按标题+
#蒸发 #对流 #厨房物理
为什么玉米粒加热后会砰地爆开成爆米花？
Why does a corn kernel pop into popcorn when heated?
玉米粒内部有少量水分和淀粉，加热时水汽化产生高压。当压力超过种皮承受极限，内核瞬间膨胀撑破外皮，淀粉糊化定型成蓬松的爆米花。
Each kernel contains a little water and starch. Heating turns the water to steam under high pressure, and when it exceeds the hull's limit the kernel suddenly expands, bursting the shell and setting the starch into a fluffy shape.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Paul Hewitt,《Conceptual Physics》Pearson 多版
Paul G. Hewitt, Conceptual Physics, Pearson, various editions
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL1930743W：Conceptual physics（按标题+
#相变 #压强 #厨房物理
为什么青菜在开水里焯一下颜色会更翠绿？
Why do green vegetables look brighter after a quick blanch?
青菜的绿色来自叶绿素，而叶绿素怕冷也怕酸。生叶细胞排列紧密、细胞间隙含空气，使光发生散射，颜色偏暗；快速焯烫能钝化破坏叶绿素的酶、赶走细胞间空气，并让细胞壁略微软化，减少光散射、增强叶绿素对绿光的反射，于是看起来更翠绿。但久煮会让叶绿素脱镁变黄褐，所以时间要短。
Green vegetables get their color from chlorophyll, which is sensitive to cold and acid. Raw leaves have tight cells and air pockets that scatter light, dulling the green; a quick blanch deactivates chlorophyll-degrading enzymes, drives air out of the cells, and slightly softens cell walls—reducing light scattering and boosting the reflection of green light, so the color looks brighter. Overcooking, however, demetallates chlorophyll to dull yellow-brown, so the dip must be brief.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
H. McGee, On Food and Cooking: The Science and Lore of the Kitchen, rev. ed., Scribner, 2004
H. McGee, On Food and Cooking: The Science and Lore of the Kitchen, rev. ed., Scribner, 2004
独立核验依据 · Independent verification: 核验依据 1 ARCHIVE 标识 onfoodcookingsci0000mcge_e4f3：On food and coo
#焯水 #光散射 #颜色
为什么新的不锈钢锅容易粘菜，养过的铸铁锅却不粘？
Why does a new stainless pan stick while a seasoned cast-iron pan does not?
粘锅是食物分子与金属表面直接成键的结果。养锅时油脂在高温下聚合成一层薄而致密的膜，既填平了微观凹坑，又把金属和食物隔开，黏附力因此大大降低。
Sticking happens when food molecules bond directly to bare metal. Seasoning polymerises oil into a thin dense film that fills microscopic pits and separates metal from food, so adhesion drops sharply.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#厨房物理 #表面 #摩擦
为什么往沸水里加盐，水的沸点会升高？
Why does adding salt to boiling water raise its boiling point?
盐溶解后形成溶液，溶质粒子占据了部分表面位置，使水分子更难逃逸成蒸汽，因此需要更高温度才能沸腾。这叫沸点升高，是稀溶液的依数性之一。
When salt dissolves it forms a solution; the solute particles occupy surface sites and make it harder for water molecules to escape as vapor, so a higher temperature is needed to boil. This is boiling-point elevation, a colligative property of dilute solutions.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Paul Hewitt,《Conceptual Physics》Pearson 多版
Paul G. Hewitt, Conceptual Physics, Pearson, various editions
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL1930743W：Conceptual physics（按标题+
#沸点 #溶液 #厨房物理
水快开的时候锅里声音最大，真正沸腾后反而变小，为什么？
Why is a kettle loudest just before boiling and quieter once it truly boils?
水将开时，锅底产生的小气泡上升到较冷的水层又被压破，这种反复崩塌会发出嘈杂的噪声。等到整锅水都到达沸点，气泡能一路浮到水面破裂，声音就柔和多了。
Just before boiling, bubbles formed at the hot bottom collapse when they rise into cooler water, and those implosions make a hissing roar. Once the whole pot reaches boiling point the bubbles survive to the surface, so the sound softens.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#沸腾 #气泡 #声音
高压锅为什么能把牛腩炖得更快？
Why does a pressure cooker soften beef brisket so much faster?
锅内压强约两个大气压，水的沸点从100℃升到约120℃。温度升高使胶原蛋白水解成明胶的速率大幅加快，所以硬的肉块很快就变酥烂。
Inside the sealed pot the pressure rises to roughly two atmospheres, pushing water's boiling point from 100 °C to about 120 °C. The extra temperature greatly speeds up the conversion of tough collagen into soft gelatin.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#高压锅 #沸点 #压强
为什么糖在热水中比在冷水中溶解得更快？
Why does sugar dissolve faster in hot water than in cold water?
温度升高使水分子运动更剧烈，撞击糖晶体的频率和无序度都增加，从而加快溶解。这是分子热运动与扩散速度随温度上升的典型表现。
Higher temperature makes water molecules move more vigorously, increasing how often and how randomly they strike the sugar crystals, which speeds dissolution. It is a typical result of faster molecular motion and diffusion at higher temperatures.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Paul Hewitt,《Conceptual Physics》Pearson 多版
Paul G. Hewitt, Conceptual Physics, Pearson, various editions
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL1930743W：Conceptual physics（按标题+
#溶解 #扩散 #厨房物理
为什么把啤酒瓶放进冰箱冷冻室，有时瓶子会从内部裂开？
Why does a beer bottle sometimes crack from the inside when left in the freezer?
水结冰时体积会膨胀约9%，啤酒里大部分是水。液体结成冰后膨胀产生很大内压，玻璃瓶承受不住就会被撑裂。
Water expands by about 9 percent when it freezes, and beer is mostly water. As the liquid turns to ice it swells and creates strong internal pressure that the glass bottle cannot withstand, so it cracks.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Paul Hewitt,《Conceptual Physics》Pearson 多版
Paul G. Hewitt, Conceptual Physics, Pearson, various editions
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL1930743W：Conceptual physics（按标题+
#凝固 #体积膨胀 #厨房物理
为什么油和水倒在一起不会混合，而且油总是浮在水面上？
Why don't oil and water mix, and why does oil always float on top of water?
油分子是疏水的非极性分子，与水分子之间的吸引力很弱，所以难以互溶。油的密度比水小，因此会浮在水面上层。
Oil molecules are nonpolar and interact weakly with water molecules, so they barely dissolve in each other. Oil is also less dense than water, so it floats on top.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Paul Hewitt,《Conceptual Physics》Pearson 多版
Paul G. Hewitt, Conceptual Physics, Pearson, various editions
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL1930743W：Conceptual physics（按标题+
#密度 #互溶性 #厨房物理
微波炉加热的饭，为什么外面烫、中间还是凉的？
Why is microwaved food scalding outside but cold in the middle?
微波在食物中会被水分吸收，能进入的深度只有一两厘米，中心主要靠热量慢慢传导过去。中途搅拌或分次加热，比一次开大火更均匀。
Microwaves are absorbed by water within one or two centimetres, so the centre only warms by slow heat conduction. Stirring midway or heating in shorter bursts gives a much more even result.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#微波炉 #穿透深度 #热传导
为什么用微波炉加热带壳鸡蛋容易爆裂？
Why does heating a shelled egg in a microwave often make it burst?
微波炉让食物内部的水分子快速振动产热，鸡蛋内部水分急剧变成蒸汽却来不及从壳内逸出。内部压力迅速升高，超过蛋壳强度就会炸开。
A microwave makes water molecules inside the food vibrate and heat rapidly. In an egg the water turns to steam too fast to escape through the shell, so internal pressure builds until it exceeds the shell strength and bursts.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Paul Hewitt,《Conceptual Physics》Pearson 多版
Paul G. Hewitt, Conceptual Physics, Pearson, various editions
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL1930743W：Conceptual physics（按标题+
#微波炉 #蒸汽压 #厨房物理
为什么煮饺子时饺子会先沉在锅底，熟了之后又浮起来？
Why do dumplings sink to the bottom of the pot at first and then float up once they are cooked?
生饺子密度比水大，所以会沉底。煮熟后馅和皮里的空气受热膨胀，加上水分渗入使整体密度变小，当平均密度小于水时就浮了起来。
Raw dumplings are denser than water, so they sink. As they cook, the air trapped inside the filling and dough expands with heat, and water seeps in, lowering the overall density until it becomes less than that of water, making them float.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Paul Hewitt,《Conceptual Physics》Pearson 多版
Paul G. Hewitt, Conceptual Physics, Pearson, various editions
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL1930743W：Conceptual physics（按标题+
#密度 #浮力 #厨房物理
为什么冰块能浮在水面上，而不是沉下去？
Why does ice float on water instead of sinking?
大多数物质固态比液态密度大，但水在4摄氏度时密度最大，结冰后分子排列成疏松的晶体，密度反而变小。因为比水轻，冰块就浮在水面。
Most substances are denser as solids, but water is densest at about 4 degrees Celsius. When it freezes, its molecules form a loose crystal structure that is actually less dense, so ice floats.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Paul Hewitt,《Conceptual Physics》Pearson 多版
Paul G. Hewitt, Conceptual Physics, Pearson, various editions
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL1930743W：Conceptual physics（按标题+
#密度 #水的反常 #厨房物理
放在冷冻室里的冰块，为什么会一天天变小？
Why do ice cubes slowly shrink in the freezer?
冰不用先化成水，也可以直接变成看不见的水汽跑掉，这叫升华。跑掉的水汽后来结在冰箱壁上，成了白霜。
Ice can turn straight into invisible vapour without melting first; that is called sublimation. The vapour later freezes onto the freezer walls as frost.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#升华 #水汽 #冰箱
冰箱塞得太满，为什么反而更费电？
Why does an overstuffed fridge use more electricity?
冰箱靠冷空气循环带走热量。塞得太满会挡住风道，冷气流不动，压缩机只好开得更久才能让各处都变冷。
A fridge cools by circulating cold air. Packing it too full blocks the airflow, so the compressor has to run longer to chill every corner.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#冰箱 #对流 #节能
普通玻璃杯倒开水会裂，耐热玻璃为什么不会？
Why does an ordinary glass crack with boiling water but borosilicate glass does not?
开水先烫到内壁，内壁想膨胀而外壁还是冷的，两层互相拉扯就产生了热应力。耐热玻璃（硼硅玻璃）的热膨胀系数只有普通玻璃的三分之一左右，同样的温差产生的应力小得多。
Boiling water expands the inner wall while the outer wall stays cold, and the mismatch creates thermal stress. Borosilicate glass expands only about a third as much for the same temperature jump, so the stress stays below the breaking point.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#热膨胀 #热应力 #玻璃
一滴水掉进热油锅里，为什么会“炸”起来？
Why does a drop of water make hot oil explode?
水滴沉到油下面被迅速加热，变成水蒸气时体积膨胀上千倍。这股突然膨胀的蒸汽把周围的油向上顶开，就成了溅射。
The droplet sinks under the oil, flashes into steam and expands by well over a thousand times in volume. That sudden expansion blasts the surrounding oil upward as spatter.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#汽化 #体积膨胀 #安全