物理学の記事

Air bubbles rising from a scuba diver in water

気泡（バブル）の科学日常の現象から高度な産業応用まで

気泡バブル物理学屈折率

2026年8月12日続きを読む →

An ampule of nitrogen oxide vapor: brown nitrogen dioxide and colorless dinitrogen tetroxide, in equilibrium

蒸気（Vapor）の物理的性質と気体との決定的な違い

蒸気臨界温度飽和蒸気圧凝縮

2026年8月12日続きを読む →

Illustration of a planar Couette flow. Since the shearing flow is opposed by friction between adjacent layers of fluid (which are in relative motion), a force is required to sustain the motion of the upper plate. The relative strength of this force is a measure of the fluid's viscosity.

粘度とは何か？流体の「ねばりけ」を決定づける物理的メカニズム

粘度動粘度ニュートン流体非ニュートン流体

2026年8月12日続きを読む →

ダニエル・ベルヌーイ流体力学と経済学の基礎を築いた天才数学者

ダニエル・ベルヌーイベルヌーイの定理流体力学期待効用理論

2026年8月12日続きを読む →

$The second-order Cauchy stress tensor T {\displaystyle \mathbf {T} } describes the stress experienced by a material at a given point. For any unit vector v {\displaystyle \mathbf {v} } , the product T ⋅ v {\displaystyle \mathbf {T} \cdot \mathbf {v} } is a vector, denoted T ( v ) {\displaystyle \mathbf {T} (\mathbf {v} )} , that quantifies the force per area along the plane perpendicular to v {\displaystyle \mathbf {v} } . This image shows, for cube faces perpendicular to e 1 , e 2 , e 3 {\displaystyle \mathbf {e} _{1},\mathbf {e} _{2},\mathbf {e} _{3}} , the corresponding stress vectors T ( e 1 ) , T ( e 2 ) , T ( e 3 ) {\displaystyle \mathbf {T} (\mathbf {e} _{1}),\mathbf {T} (\mathbf {e} _{2}),\mathbf {T} (\mathbf {e} _{3})} along those faces. Because the stress tensor takes one vector as input and gives one vector as output, it is a second-order tensor.$