马朗戈尼效应为什么让酒泪沿杯壁爬升？
Why does the Marangoni effect make wine tears climb the glass?
酒液表面酒精蒸发快处表面张力高、未蒸发处较低，表面张力梯度产生切向应力把液体沿壁拉上去；重力再使其成泪滴回落，形成酒泪。
Where alcohol evaporates, surface tension is higher; the gradient drives a Marangoni stress pulling liquid up the wall, then gravity forms falling tears.
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
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#流体 #马朗戈尼 #表面张力
为什么涡量在理想不可压流中沿流管守恒（开尔文定理）？
Why is vorticity conserved along stream tubes in ideal incompressible flow—Kelvin's theorem?
在无黏、正压且外力有势时，随体导数 DΓ/Dt=0（开尔文环量守恒），据此涡管强度沿流管不变；这解释台风眼、烟圈等为何能维持旋转结构。
For inviscid barotropic flow with potential body forces, DΓ/Dt=0 (Kelvin's theorem), so vortex-tube strength is conserved along stream tubes—explaining persistent vortices like tornado eyes and smoke rings.
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
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#流体 #涡量 #开尔文
雷诺数如何决定流动是层流还是湍流？
How does the Reynolds number decide laminar vs turbulent flow?
Re=ρvL/μ 比较惯性力与黏性力；小 Re 时黏性主导、流动平滑分层（层流），大 Re 时惯性主导、小扰动被放大成混沌湍流；管流临界值约2000–4000。
Re=ρvL/μ compares inertia to viscosity; low Re is smooth (laminar), high Re lets perturbations grow into turbulence, with pipe-flow transition near Re ~2000–4000.
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
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#流体 #雷诺数 #湍流
为什么高尔夫球表面有凹坑反而飞得更远？
Why do golf balls with dimples fly farther?
凹坑让边界层转为湍流，湍流边界层更不容易分离，从而减小尾流与压差阻力（阻力）；升阻比改善，球能借升力滑翔更远。
Dimples trigger a turbulent boundary layer that separates later, shrinking the wake and pressure drag; better lift-to-drag lets the ball glide farther.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#流体 #阻力 #边界层
为什么罐头底部常常凹进去？
Why is the bottom of a food can often concave?
密封加热杀菌后冷却，罐内气压低于外界，外界大气压把罐底压得微微内凹；这也帮助判断罐头是否漏气胀罐。
After sealing and heating, cooling lowers the internal pressure, so outside air pressure pushes the base slightly inward; a bulged can instead signals spoilage.
难度 进阶 · 适合 初中(12-15)
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
#大气压 #密封 #罐头
为什么水在细管里会自己往上爬（毛细现象）？
Why does water climb thin tubes by itself—capillarity?
水能润湿玻璃，弯月面处表面张力向上拉、同时液体与管壁粘附；若管够细，这股力超过液柱重力，水就上升到 h≈2γcosθ/(ρgr)。
Water wets glass; surface tension at the meniscus plus adhesion pulls upward, and in a narrow tube this overcomes the column's weight, rising to h≈2γcosθ/(ρgr).
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#流体 #毛细 #表面张力
为什么吸管能吸上饮料？
Why does a straw lift your drink?
你吸气时吸管里空气变少、压强降低，杯中液面上方的大气压把饮料压进吸管、送进嘴里；不是吸力把液体拉上来，而是外面空气推上来。
Sucking lowers pressure inside the straw; the higher atmospheric pressure on the cup pushes the drink up the straw into your mouth—it's pushed, not pulled.
难度 入门 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
大气压
Atmospheric pressure
#流体 #压强 #大气
为什么洗澡时浴缸里的小鸭子会跟着水流转圈？
Why does a bath-duck swirl with the water?
你搅动水时，水分子带着小鸭子一起动；水转圈时靠近中心的转得慢、外面的转得快，鸭子就被水流推着打转，直到水停下。
When you swirl water, the molecules carry the duck along; the moving water pushes it in circles until the motion fades.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#流体 #涡 #流