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Multipath Pipeline Problems

Fluid Mechanics · FE Reference Handbook section

Fluid Mechanics
6 formulas
10 exam-style examples
~57 min
All Fluid Mechanics lectures

Handbook notes for this section

Definitions and conditions exactly as the handbook states them.

  • For pipes in parallel, the head loss is the same in each pipe.
  • The total flowrate Q is the sum of the flowrates in the parallel pipes.
  • The resultant force in a given direction acting on the fluid equals the rate of change of momentum of the fluid.

Core formulas for this FE topic

Definitions, applicability, units, assumptions and worked examples for each relation.

Worked exam-style examples

The four ways this section is written on the real exam — thoughts first, then equations, then substitution.

Example 1
Multipath pipeline problems (continuity/head-loss balance) — solve for total flow — Multipath Pipeline Problems

a multipath pipeline with two parallel branches around an obstruction Given flow in branch 1 (Q_1) = 0.2200 m^3/s; flow in branch 2 (Q_2) = 0.2250 m^3/s, determine the total flow (Q) in m^3/s.

Given

  • flowinbranch1(Q1)=0.2200m3/sflow in branch 1 (Q_1) = 0.2200 m^3/s
  • flowinbranch2(Q2)=0.2250m3/sflow in branch 2 (Q_2) = 0.2250 m^3/s

Find

total flow (Q), in m^3/s

Start with the thinking

  • The governing relation printed in this handbook section is Multipath pipeline problems (continuity/head-loss balance).
  • Everything except Q is given, so isolate Q symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Multipath pipeline problems split total flow between parallel branches so head loss is equal in each path.
D₁=200D₂=150Q1Q2

Figure 1 — schematic for Multipath pipeline problems (continuity/head-loss balance) — solve for total flow — Multipath Pipeline Problems

Step-by-step solution

  1. Step 1 — State the governing relation:

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}
  2. Step 2 — Rearrange the relation so that Q stands alone on the left-hand side.

  3. Step 3

    Listthegivens:flowinbranch1(Q1)=0.2200m3/s,flowinbranch2(Q2)=0.2250m3/sList the givens: flow in branch 1 (Q_1) = 0.2200 m^3/s, flow in branch 2 (Q_2) = 0.2250 m^3/s
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    Q = 0.4450\ \text{m^3/s}
  6. Step 6 — Check: returning Q = 0.4450 m^3/s to

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q = 0.4450\ \text{m^3/s}

Why the other options are there

  • 0.8900 — kept a factor of two that cancels in the correct rearrangement.
  • 0.2225 — dropped that same factor in the other direction.
  • 0.4895 — rounded an intermediate value before the final step.

Reference: FE Handbook — Multipath Pipeline Problems

Example 2
Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 1 — Multipath Pipeline Problems (2)

multipath pipeline problems in a looped water distribution network Given total flow (Q) = 0.3550 m^3/s; flow in branch 2 (Q_2) = 0.0350 m^3/s, determine the flow in branch 1 (Q_1) in m^3/s.

Given

  • totalflow(Q)=0.3550m3/stotal flow (Q) = 0.3550 m^3/s
  • flowinbranch2(Q2)=0.0350m3/sflow in branch 2 (Q_2) = 0.0350 m^3/s

Find

flow in branch 1 (Q_1), in m^3/s

Start with the thinking

  • The governing relation printed in this handbook section is Multipath pipeline problems (continuity/head-loss balance).
  • Everything except Q_1 is given, so isolate Q_1 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Multipath pipeline problems split total flow between parallel branches so head loss is equal in each path.
D₁=200D₂=150Q1Q2

Figure 2 — schematic for Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 1 — Multipath Pipeline Problems (2)

Step-by-step solution

  1. Step 1 — State the governing relation:

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}
  2. Step 2 — Rearrange the relation so that Q_1 stands alone on the left-hand side.

  3. Step 3

    Listthegivens:totalflow(Q)=0.3550m3/s,flowinbranch2(Q2)=0.0350m3/sList the givens: total flow (Q) = 0.3550 m^3/s, flow in branch 2 (Q_2) = 0.0350 m^3/s
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    Q_{1} = 0.3200\ \text{m^3/s}
  6. Step 6 — Check: returning Q_1 = 0.3200 m^3/s to

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q_{1} = 0.3200\ \text{m^3/s}

Why the other options are there

  • 0.6400 — kept a factor of two that cancels in the correct rearrangement.
  • 0.1600 — dropped that same factor in the other direction.
  • 0.3520 — rounded an intermediate value before the final step.

Reference: FE Handbook — Multipath Pipeline Problems

Example 3
Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 2 — Multipath Pipeline Problems (3)

a multipath pipeline delivering flow to two service pipes Given total flow (Q) = 0.1000 m^3/s; flow in branch 1 (Q_1) = 0.2900 m^3/s, determine the flow in branch 2 (Q_2) in m^3/s.

Given

  • totalflow(Q)=0.1000m3/stotal flow (Q) = 0.1000 m^3/s
  • flowinbranch1(Q1)=0.2900m3/sflow in branch 1 (Q_1) = 0.2900 m^3/s

Find

flow in branch 2 (Q_2), in m^3/s

Start with the thinking

  • The governing relation printed in this handbook section is Multipath pipeline problems (continuity/head-loss balance).
  • Everything except Q_2 is given, so isolate Q_2 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Multipath pipeline problems split total flow between parallel branches so head loss is equal in each path.
D₁=200D₂=150Q1Q2

Figure 3 — schematic for Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 2 — Multipath Pipeline Problems (3)

Step-by-step solution

  1. Step 1 — State the governing relation:

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}
  2. Step 2 — Rearrange the relation so that Q_2 stands alone on the left-hand side.

  3. Step 3

    Listthegivens:totalflow(Q)=0.1000m3/s,flowinbranch1(Q1)=0.2900m3/sList the givens: total flow (Q) = 0.1000 m^3/s, flow in branch 1 (Q_1) = 0.2900 m^3/s
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    Q_{2} = -0.1900\ \text{m^3/s}
  6. Step 6 — Check: returning Q_2 = -0.1900 m^3/s to

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q_{2} = -0.1900\ \text{m^3/s}

Why the other options are there

  • -0.3800 — kept a factor of two that cancels in the correct rearrangement.
  • -0.0950 — dropped that same factor in the other direction.
  • -0.2090 — rounded an intermediate value before the final step.

Reference: FE Handbook — Multipath Pipeline Problems

Example 4
Multipath pipeline problems (continuity/head-loss balance) — solve for total flow (case 2) — Multipath Pipeline Problems (4)

a multipath pipeline with two parallel branches around an obstruction Given flow in branch 1 (Q_1) = 0.2150 m^3/s; flow in branch 2 (Q_2) = 0.0250 m^3/s, determine the total flow (Q) in m^3/s.

Given

  • flowinbranch1(Q1)=0.2150m3/sflow in branch 1 (Q_1) = 0.2150 m^3/s
  • flowinbranch2(Q2)=0.0250m3/sflow in branch 2 (Q_2) = 0.0250 m^3/s

Find

total flow (Q), in m^3/s

Start with the thinking

  • The governing relation printed in this handbook section is Multipath pipeline problems (continuity/head-loss balance).
  • Everything except Q is given, so isolate Q symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Multipath pipeline problems split total flow between parallel branches so head loss is equal in each path.
D₁=200D₂=150Q1Q2

Figure 4 — schematic for Multipath pipeline problems (continuity/head-loss balance) — solve for total flow (case 2) — Multipath Pipeline Problems (4)

Step-by-step solution

  1. Step 1 — State the governing relation:

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}
  2. Step 2 — Rearrange the relation so that Q stands alone on the left-hand side.

  3. Step 3

    Listthegivens:flowinbranch1(Q1)=0.2150m3/s,flowinbranch2(Q2)=0.0250m3/sList the givens: flow in branch 1 (Q_1) = 0.2150 m^3/s, flow in branch 2 (Q_2) = 0.0250 m^3/s
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    Q = 0.2400\ \text{m^3/s}
  6. Step 6 — Check: returning Q = 0.2400 m^3/s to

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q = 0.2400\ \text{m^3/s}

Why the other options are there

  • 0.4800 — kept a factor of two that cancels in the correct rearrangement.
  • 0.1200 — dropped that same factor in the other direction.
  • 0.2640 — rounded an intermediate value before the final step.

Reference: FE Handbook — Multipath Pipeline Problems

Example 5
Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 1 (case 2) — Multipath Pipeline Problems (5)

multipath pipeline problems in a looped water distribution network Given total flow (Q) = 0.3250 m^3/s; flow in branch 2 (Q_2) = 0.1850 m^3/s, determine the flow in branch 1 (Q_1) in m^3/s.

Given

  • totalflow(Q)=0.3250m3/stotal flow (Q) = 0.3250 m^3/s
  • flowinbranch2(Q2)=0.1850m3/sflow in branch 2 (Q_2) = 0.1850 m^3/s

Find

flow in branch 1 (Q_1), in m^3/s

Start with the thinking

  • The governing relation printed in this handbook section is Multipath pipeline problems (continuity/head-loss balance).
  • Everything except Q_1 is given, so isolate Q_1 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Multipath pipeline problems split total flow between parallel branches so head loss is equal in each path.
D₁=200D₂=150Q1Q2

Figure 5 — schematic for Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 1 (case 2) — Multipath Pipeline Problems (5)

Step-by-step solution

  1. Step 1 — State the governing relation:

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}
  2. Step 2 — Rearrange the relation so that Q_1 stands alone on the left-hand side.

  3. Step 3

    Listthegivens:totalflow(Q)=0.3250m3/s,flowinbranch2(Q2)=0.1850m3/sList the givens: total flow (Q) = 0.3250 m^3/s, flow in branch 2 (Q_2) = 0.1850 m^3/s
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    Q_{1} = 0.1400\ \text{m^3/s}
  6. Step 6 — Check: returning Q_1 = 0.1400 m^3/s to

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q_{1} = 0.1400\ \text{m^3/s}

Why the other options are there

  • 0.2800 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0700 — dropped that same factor in the other direction.
  • 0.1540 — rounded an intermediate value before the final step.

Reference: FE Handbook — Multipath Pipeline Problems

Example 6
Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 2 (case 2) — Multipath Pipeline Problems (6)

a multipath pipeline delivering flow to two service pipes Given total flow (Q) = 0.1300 m^3/s; flow in branch 1 (Q_1) = 0.2850 m^3/s, determine the flow in branch 2 (Q_2) in m^3/s.

Given

  • totalflow(Q)=0.1300m3/stotal flow (Q) = 0.1300 m^3/s
  • flowinbranch1(Q1)=0.2850m3/sflow in branch 1 (Q_1) = 0.2850 m^3/s

Find

flow in branch 2 (Q_2), in m^3/s

Start with the thinking

  • The governing relation printed in this handbook section is Multipath pipeline problems (continuity/head-loss balance).
  • Everything except Q_2 is given, so isolate Q_2 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Multipath pipeline problems split total flow between parallel branches so head loss is equal in each path.
D₁=200D₂=150Q1Q2

Figure 6 — schematic for Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 2 (case 2) — Multipath Pipeline Problems (6)

Step-by-step solution

  1. Step 1 — State the governing relation:

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}
  2. Step 2 — Rearrange the relation so that Q_2 stands alone on the left-hand side.

  3. Step 3

    Listthegivens:totalflow(Q)=0.1300m3/s,flowinbranch1(Q1)=0.2850m3/sList the givens: total flow (Q) = 0.1300 m^3/s, flow in branch 1 (Q_1) = 0.2850 m^3/s
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    Q_{2} = -0.1550\ \text{m^3/s}
  6. Step 6 — Check: returning Q_2 = -0.1550 m^3/s to

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q_{2} = -0.1550\ \text{m^3/s}

Why the other options are there

  • -0.3100 — kept a factor of two that cancels in the correct rearrangement.
  • -0.0775 — dropped that same factor in the other direction.
  • -0.1705 — rounded an intermediate value before the final step.

Reference: FE Handbook — Multipath Pipeline Problems

Example 7
Multipath pipeline problems (continuity/head-loss balance) — solve for total flow (case 3) — Multipath Pipeline Problems (7)

a multipath pipeline with two parallel branches around an obstruction Given flow in branch 1 (Q_1) = 0.2200 m^3/s; flow in branch 2 (Q_2) = 0.0750 m^3/s, determine the total flow (Q) in m^3/s.

Given

  • flowinbranch1(Q1)=0.2200m3/sflow in branch 1 (Q_1) = 0.2200 m^3/s
  • flowinbranch2(Q2)=0.0750m3/sflow in branch 2 (Q_2) = 0.0750 m^3/s

Find

total flow (Q), in m^3/s

Start with the thinking

  • The governing relation printed in this handbook section is Multipath pipeline problems (continuity/head-loss balance).
  • Everything except Q is given, so isolate Q symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Multipath pipeline problems split total flow between parallel branches so head loss is equal in each path.
D₁=200D₂=150Q1Q2

Figure 7 — schematic for Multipath pipeline problems (continuity/head-loss balance) — solve for total flow (case 3) — Multipath Pipeline Problems (7)

Step-by-step solution

  1. Step 1 — State the governing relation:

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}
  2. Step 2 — Rearrange the relation so that Q stands alone on the left-hand side.

  3. Step 3

    Listthegivens:flowinbranch1(Q1)=0.2200m3/s,flowinbranch2(Q2)=0.0750m3/sList the givens: flow in branch 1 (Q_1) = 0.2200 m^3/s, flow in branch 2 (Q_2) = 0.0750 m^3/s
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    Q = 0.2950\ \text{m^3/s}
  6. Step 6 — Check: returning Q = 0.2950 m^3/s to

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q = 0.2950\ \text{m^3/s}

Why the other options are there

  • 0.5900 — kept a factor of two that cancels in the correct rearrangement.
  • 0.1475 — dropped that same factor in the other direction.
  • 0.3245 — rounded an intermediate value before the final step.

Reference: FE Handbook — Multipath Pipeline Problems

Example 8
Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 1 (case 3) — Multipath Pipeline Problems (8)

multipath pipeline problems in a looped water distribution network Given total flow (Q) = 0.5000 m^3/s; flow in branch 2 (Q_2) = 0.1700 m^3/s, determine the flow in branch 1 (Q_1) in m^3/s.

Given

  • totalflow(Q)=0.5000m3/stotal flow (Q) = 0.5000 m^3/s
  • flowinbranch2(Q2)=0.1700m3/sflow in branch 2 (Q_2) = 0.1700 m^3/s

Find

flow in branch 1 (Q_1), in m^3/s

Start with the thinking

  • The governing relation printed in this handbook section is Multipath pipeline problems (continuity/head-loss balance).
  • Everything except Q_1 is given, so isolate Q_1 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Multipath pipeline problems split total flow between parallel branches so head loss is equal in each path.
D₁=200D₂=150Q1Q2

Figure 8 — schematic for Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 1 (case 3) — Multipath Pipeline Problems (8)

Step-by-step solution

  1. Step 1 — State the governing relation:

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}
  2. Step 2 — Rearrange the relation so that Q_1 stands alone on the left-hand side.

  3. Step 3

    Listthegivens:totalflow(Q)=0.5000m3/s,flowinbranch2(Q2)=0.1700m3/sList the givens: total flow (Q) = 0.5000 m^3/s, flow in branch 2 (Q_2) = 0.1700 m^3/s
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    Q_{1} = 0.3300\ \text{m^3/s}
  6. Step 6 — Check: returning Q_1 = 0.3300 m^3/s to

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q_{1} = 0.3300\ \text{m^3/s}

Why the other options are there

  • 0.6600 — kept a factor of two that cancels in the correct rearrangement.
  • 0.1650 — dropped that same factor in the other direction.
  • 0.3630 — rounded an intermediate value before the final step.

Reference: FE Handbook — Multipath Pipeline Problems

Example 9
Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 2 (case 3) — Multipath Pipeline Problems (9)

a multipath pipeline delivering flow to two service pipes Given total flow (Q) = 0.0550 m^3/s; flow in branch 1 (Q_1) = 0.1300 m^3/s, determine the flow in branch 2 (Q_2) in m^3/s.

Given

  • totalflow(Q)=0.0550m3/stotal flow (Q) = 0.0550 m^3/s
  • flowinbranch1(Q1)=0.1300m3/sflow in branch 1 (Q_1) = 0.1300 m^3/s

Find

flow in branch 2 (Q_2), in m^3/s

Start with the thinking

  • The governing relation printed in this handbook section is Multipath pipeline problems (continuity/head-loss balance).
  • Everything except Q_2 is given, so isolate Q_2 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Multipath pipeline problems split total flow between parallel branches so head loss is equal in each path.
D₁=200D₂=150Q1Q2

Figure 9 — schematic for Multipath pipeline problems (continuity/head-loss balance) — solve for flow in branch 2 (case 3) — Multipath Pipeline Problems (9)

Step-by-step solution

  1. Step 1 — State the governing relation:

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}
  2. Step 2 — Rearrange the relation so that Q_2 stands alone on the left-hand side.

  3. Step 3

    Listthegivens:totalflow(Q)=0.0550m3/s,flowinbranch1(Q1)=0.1300m3/sList the givens: total flow (Q) = 0.0550 m^3/s, flow in branch 1 (Q_1) = 0.1300 m^3/s
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    Q_{2} = -0.0750\ \text{m^3/s}
  6. Step 6 — Check: returning Q_2 = -0.0750 m^3/s to

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q_{2} = -0.0750\ \text{m^3/s}

Why the other options are there

  • -0.1500 — kept a factor of two that cancels in the correct rearrangement.
  • -0.0375 — dropped that same factor in the other direction.
  • -0.0825 — rounded an intermediate value before the final step.

Reference: FE Handbook — Multipath Pipeline Problems

Example 10
Multipath pipeline problems (continuity/head-loss balance) — solve for total flow (case 4) — Multipath Pipeline Problems (10)

a multipath pipeline with two parallel branches around an obstruction Given flow in branch 1 (Q_1) = 0.2400 m^3/s; flow in branch 2 (Q_2) = 0.1150 m^3/s, determine the total flow (Q) in m^3/s.

Given

  • flowinbranch1(Q1)=0.2400m3/sflow in branch 1 (Q_1) = 0.2400 m^3/s
  • flowinbranch2(Q2)=0.1150m3/sflow in branch 2 (Q_2) = 0.1150 m^3/s

Find

total flow (Q), in m^3/s

Start with the thinking

  • The governing relation printed in this handbook section is Multipath pipeline problems (continuity/head-loss balance).
  • Everything except Q is given, so isolate Q symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Multipath pipeline problems split total flow between parallel branches so head loss is equal in each path.
D₁=200D₂=150Q1Q2

Figure 10 — schematic for Multipath pipeline problems (continuity/head-loss balance) — solve for total flow (case 4) — Multipath Pipeline Problems (10)

Step-by-step solution

  1. Step 1 — State the governing relation:

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}
  2. Step 2 — Rearrange the relation so that Q stands alone on the left-hand side.

  3. Step 3

    Listthegivens:flowinbranch1(Q1)=0.2400m3/s,flowinbranch2(Q2)=0.1150m3/sList the givens: flow in branch 1 (Q_1) = 0.2400 m^3/s, flow in branch 2 (Q_2) = 0.1150 m^3/s
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    Q = 0.3550\ \text{m^3/s}
  6. Step 6 — Check: returning Q = 0.3550 m^3/s to

    Q=Q1+Q2,hf,1=hf,2Q = Q_1 + Q_2, \qquad h_{f,1} = h_{f,2}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q = 0.3550\ \text{m^3/s}

Why the other options are there

  • 0.7100 — kept a factor of two that cancels in the correct rearrangement.
  • 0.1775 — dropped that same factor in the other direction.
  • 0.3905 — rounded an intermediate value before the final step.

Reference: FE Handbook — Multipath Pipeline Problems

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