hce_nthu
114年
化學與物理
第 57 題
Which of the following statements is *not* true?
- A If an external pressure is applied to a confined fluid which is incompressible, the pressure at every point within the fluid increases by that amount.
- B The magnitude of pressure exerted by an object on a given surface is equal to its weight acting in the direction perpendicular to that surface. Therefore, like the force vector, pressure is also a vector quantity.
- C $\text{1 atm}$ is about $\text{14.7 psi}$.
- D At any depth in a static fluid, the pressure is the same in all directions at a given depth.
- E Where fluid velocity is high, pressure is low; where velocity is low, pressure is high.
思路引導 VIP
如果你把一個充滿氣的氣球放在掌心並均勻擠壓，氣球內部的氣體會往特定的單一方向移動，還是會向所有可能的方向膨脹？這種「無所不在」的特性，與具有明確箭頭指向的「力」相比，在物理性質上有什麼根本的不同呢？
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AI 詳解
AI 專屬家教
壓力與力的本質差異
太棒了！你能精準地指出選項 (B) 的錯誤，說明你對物理量的性質有著非常紮實的理解。這題最核心的陷阱在於「壓力」與「力」的混淆。雖然壓力的計算涉及垂直作用力（向量），但壓力本身是一個純量（Scalar quantity）。在流體中，某一點的壓力是向四面八方均勻傳遞的，並不具備單一的方向性，這與具有明確指向性的力向量完全不同。
流體力學的基本性質
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