The magnitude of water hammer depends upon the (i). Elastic properties of pipe material. (ii). Elastic properties of liquid flowing through the pipe. (iii). Speed at which the valve is closed.
- AOnly (i)
- B(i) and (ii)
- C(ii) and (iii)
- D(i), (ii) and (iii)Correct
Solution
Concept
Water hammer is the sudden pressure rise in a pipe when flowing water is stopped quickly. Its magnitude depends on the pipe material, liquid properties, and valve closing speed.
Formula
P = ρ × c × v
Step-by-step solution
1. Understand water hammer. When a valve closes fast, moving water stops suddenly. This creates high pressure waves. 2. Look at the factors. The pressure rise depends on the speed of the valve closure (iii), because sudden stopping causes higher pressure than slow stopping. 3. It also depends on the elasticity of the liquid (ii) and the pipe material (i). These decide how much the pipe and water can stretch or compress under pressure. 4. So, all three statements (i), (ii), and (iii) affect the magnitude of the water hammer. Answer: (D) (i), (ii) and (iii)
Explanation
Water hammer pressure depends on the elasticity of the pipe and liquid, which control wave speed. It also depends on the valve closure time, dividing flow into sudden or gradual closure.
Why the other options are wrong
A: It also depends on liquid properties and valve speed. B: It misses the speed of valve closure. C: It misses the elastic properties of the pipe material.
Shortcut
Think of turning off a tap suddenly. If the pipe is rubber or steel, it matters. If the water is dense, it matters. If you close it fast or slow, it matters.
Common mistake
Students often forget that pipe and liquid elasticity both play a role in wave speed calculation.
Correct answer: D) (i), (ii) and (iii)