In a pipe network,
- Athe algebraic sum of discharges around each elementary circuit must be zero
- Bthe head at each node must be the same
- Cthe algebraic sum of the piezometric head drops around each elementary circuit is zeroCorrect
- Dthe piezometric head loss in each line of a circuit is the same
Solution
Concept
Hardy Cross principles
Formula
Σhf = 0
Step-by-step solution
1. Around a loop the algebraic sum of head losses is zero.
Explanation
Head drops around a closed circuit sum to zero.
Why the other options are wrong
The sum of discharges is zero at nodes, not loops.
Shortcut
Loop: Σh = 0; node: ΣQ = 0.
Correct answer: C) the algebraic sum of the piezometric head drops around each elementary circuit is zero