High water hammer pressure can cause breakage and damage to a pipeline. The property of a fluid which is accountable for the problem of water hammer is
- AdensityCorrect
- Bviscosity
- Cfluidity
- Dsurface tension
Solution
Concept
Water hammer pressure depends on the fluid's inertia (density) and compressibility, through the pressure wave speed.
Formula
Δp = ρ c V, where c = √(K/ρ)
Step-by-step solution
1. Water hammer happens when flowing water is suddenly stopped, for example by quick valve closure. 2. The momentum of the moving water (mass = density × volume) is destroyed suddenly, which creates a pressure wave. 3. The pressure rise is Δp = ρ c V, so it depends directly on density ρ. 4. Viscosity, fluidity and surface tension do not govern this effect. 5. Answer = density, option (A).
Explanation
Water hammer is caused by suddenly stopping a moving mass of liquid. The pressure rise Δp = ρcV depends on the fluid's density and its compressibility (bulk modulus K). Among the given options, density is the right choice.
Why the other options are wrong
(B) Viscosity only causes friction loss and damping; it does not cause the pressure surge. (C) Fluidity is just the ability to flow (the inverse of viscosity) and is not relevant here. (D) Surface tension matters only at free surfaces and small scales, not inside pipes.
Shortcut
Δp = ρcV, so pick the option that appears in this formula: density.
Common mistake
Choosing viscosity because it is linked to pipe flow losses.
Correct answer: A) density