The pressure rise due to water hammer caused by sudden closure of the discharge (of velocity v) through the rigid pipe is (assume, fluid density as 1225 kg/m³, elasticity constant as E and bulk modulus as K, t = thickness of pipe wall, d = diameter of pipe)
- A35 v √KCorrect
- B3.5 v √K
- C[1025 v²/(1/K + Ed/t)]1/2
- D[1025 v/(1/K + Ed/t)]1/2
Solution
Concept
Pressure rise in a rigid pipe
Formula
p = ρ c v; c = √(K/ρ)
Step-by-step solution
1. For a rigid pipe c = √(K/ρ). 2. p = ρ c v = v √(ρ K) = v √(1225 K) = 35 v √K.
Explanation
√1225 = 35.
Why the other options are wrong
The other options are the elastic-pipe form with wrong powers/densities.
Shortcut
p = v√(ρK).
Correct answer: A) 35 v √K