TRB Poly. Tech. Lect. 2012
⭕ A. maximum
⭕ B. unpredictable
⭕ C. zero
⭕ D. higher
📚 Explanation:
In fluid mechanics, shear stress is generated only when fluid particles move relative to one another. When a fluid is at rest, all its particles are stationary and there is no velocity gradient between layers.
🔹 Since shear stress is directly related to fluid motion, it becomes zero when the fluid is not flowing.
🔹 Only normal stresses (like pressure) act on fluid at rest.
In fluid mechanics, shear stress is generated only when fluid particles move relative to one another. When a fluid is at rest, all its particles are stationary and there is no velocity gradient between layers.
🔹 Since shear stress is directly related to fluid motion, it becomes zero when the fluid is not flowing.
🔹 Only normal stresses (like pressure) act on fluid at rest.
👉 Therefore, the correct answer is: C. zero
Key Features of Fluid at Rest:
- No relative motion between fluid layers
- Shear stress is completely absent
- Only pressure forces (normal stresses) act within the fluid
- Used in the analysis of hydrostatics
- Basic concept in fluid mechanics and civil engineering design
