An ideal flow of any fluid must satisfy

Options

A. 1. Pascal law
B. 2. Stokes' law
C. 3. Continuity equation
D. 4. Bernoulli's theorem

Answer

To determine what an ideal flow of any fluid must satisfy, we need to analyze the definitions and implications of the terms involved.

### Step-by-Step Solution:

1. **Understanding Ideal Flow**:
- An ideal flow refers to the flow of an incompressible fluid that flows steadily without any friction. This means that the viscosity (η) of the fluid is considered to be zero.

2. **Evaluating the Options**:
- **Pascal's Law**:
- This law states that a pressure change at any point in a static fluid is transmitted undiminished throughout the fluid. Since ideal flow refers to dynamic conditions (not static), Pascal's law does not apply here.
- **Stokes' Law**:
- Stokes' law describes the drag force experienced by a sphere moving through a viscous fluid. Since ideal flow assumes zero viscosity, Stokes' law is also not applicable.
- **Continuity Equation**:
- The continuity equation arises from the conservation of mass principle. It states that the mass flow rate must remain constant in a fluid flow. This equation is valid for both ideal and real fluids, making it applicable to ideal flow.
- **Bernoulli's Theorem**:
- Bernoulli's theorem relates to the conservation of energy in fluid flow. It applies to laminar flow conditions, which typically involve some viscosity. Therefore, it is not applicable to ideal flow where viscosity is zero.

3. **Conclusion**:
- The only option that satisfies the conditions of an ideal flow is the **continuity equation**.

Thus, the correct answer is the **continuity equation**.