In turbulent flow the velocity of the liquid molecules in contact with the walls of the tube.

Options

A. zero
B. maximum
C. in between zero and maximum
D. equal to critical velocity

Answer

To solve the question regarding the velocity of liquid molecules in contact with the walls of a tube during turbulent flow, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Turbulent Flow**:
- In turbulent flow, the fluid moves in a chaotic manner, with eddies and vortices. This type of flow occurs at high velocities and is characterized by irregular fluctuations in pressure and flow velocity.

2. **Velocity at the Wall**:
- According to the principles of fluid dynamics, the velocity of a fluid in contact with a solid boundary (like the walls of a tube) is always zero. This is due to the no-slip condition, which states that the fluid adheres to the surface of the boundary.

3. **Implications of the No-Slip Condition**:
- The no-slip condition implies that as you move away from the wall into the fluid, the velocity of the fluid increases until it reaches a maximum value at the center of the tube. However, right at the wall, the velocity is zero.

4. **Conclusion**:
- Therefore, in turbulent flow, the velocity of the liquid molecules in contact with the walls of the tube is indeed 0.

5. **Final Answer**:
- The correct option is that the velocity of the liquid molecules in contact with the walls of the tube is 0.