What happens to friction loss if hose diameter increases while maintaining the same flow?

What happens to friction loss if hose diameter increases while maintaining the same flow?

• A. Increases
• B. Decreases
• C. Remains the same
• D. Doubles

Answer: (B)

Friction loss depends on how fast water moves through the hose. For a fixed flow rate, widening the hose increases the cross-sectional area, which lowers the water velocity (V = Q/A). Lower velocity reduces the shear interactions with the hose walls, so less energy is dissipated as friction per unit length. In practical terms, the pressure drop caused by friction decreases when you use a larger diameter hose at the same flow. That’s why the correct outcome is that friction loss decreases.

Friction loss depends on how fast water moves through the hose. For a fixed flow rate, widening the hose increases the cross-sectional area, which lowers the water velocity (V = Q/A). Lower velocity reduces the shear interactions with the hose walls, so less energy is dissipated as friction per unit length. In practical terms, the pressure drop caused by friction decreases when you use a larger diameter hose at the same flow. That’s why the correct outcome is that friction loss decreases.