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Reel and Paddle

Environmental Engineering · FE Reference Handbook section

Environmental Engineering
8 formulas
10 exam-style examples
~60 min
All Environmental Engineering lectures

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
Reel and Paddle — solve for power dissipated — Reel and Paddle

reel and paddle flocculator power dissipation calculation Given drag coefficient of paddle (C_D) = 1.9100; fluid density (rho) = 995.0 kg/m^3; paddle area (A) = 3.9000 m^2; paddle velocity relative to water (v_p) = 0.3400 m/s, determine the power dissipated (P) in W.

Given

  • dragcoefficientofpaddle(CD)=1.9100drag coefficient of paddle (C_D) = 1.9100
  • fluiddensity(rho)=995.0kg/m3fluid density (rho) = 995.0 kg/m^3
  • paddlearea(A)=3.9000m2paddle area (A) = 3.9000 m^2
  • paddlevelocityrelativetowater(vp)=0.3400m/spaddle velocity relative to water (v_p) = 0.3400 m/s

Find

power dissipated (P), in W

Start with the thinking

  • The governing relation printed in this handbook section is Reel and Paddle.
  • Everything except P is given, so isolate P 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.
  • Reel and paddle flocculators dissipate power in proportion to paddle drag, area, and relative velocity through the water.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}
  2. Step 2 — Rearrange symbolically for P:

    P=CDρAvp32P = \dfrac{C_D\rho A v_p^3}{2}
  3. Step 3 — List the givens: drag coefficient of paddle (C_D) = 1.9100, fluid density (rho) = 995.0 kg/m^3, paddle area (A) = 3.9000 m^2, paddle velocity relative to water (v_p) = 0.3400 m/s.

  4. Step 4 — Substitute the given values:

    P=CD995.03.9000vp32P = \dfrac{C_D995.0 3.9000 v_p^3}{2}
  5. Step 5 — Evaluate:

    P=145.7 WP = 145.7\ \text{W}
  6. Step 6 — Check: returning P = 145.7 W to

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}

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

Answer:
P=145.7 WP = 145.7\ \text{W}

Why the other options are there

  • 291.3 — kept a factor of two that cancels in the correct rearrangement.
  • 72.8279 — dropped that same factor in the other direction.
  • 160.2 — rounded an intermediate value before the final step.

Reference: FE Handbook — Reel and Paddle Flocculator

Example 2
Reel and Paddle — solve for paddle area — Reel and Paddle (2)

reel and paddle mixer design for flocculation basin Given drag coefficient of paddle (C_D) = 1.3200; fluid density (rho) = 996.5 kg/m^3; paddle velocity relative to water (v_p) = 0.5200 m/s; power dissipated (P) = 3,069 W, determine the paddle area (A) in m^2.

Given

  • dragcoefficientofpaddle(CD)=1.3200drag coefficient of paddle (C_D) = 1.3200
  • fluiddensity(rho)=996.5kg/m3fluid density (rho) = 996.5 kg/m^3
  • paddlevelocityrelativetowater(vp)=0.5200m/spaddle velocity relative to water (v_p) = 0.5200 m/s
  • powerdissipated(P)=3,069Wpower dissipated (P) = 3,069 W

Find

paddle area (A), in m^2

Start with the thinking

  • The governing relation printed in this handbook section is Reel and Paddle.
  • Everything except A is given, so isolate A 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.
  • Reel and paddle flocculators dissipate power in proportion to paddle drag, area, and relative velocity through the water.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}
  2. Step 2 — Rearrange symbolically for A:

    A=2PCDρvp3A = \dfrac{2P}{C_D\rho v_p^3}
  3. Step 3 — List the givens: drag coefficient of paddle (C_D) = 1.3200, fluid density (rho) = 996.5 kg/m^3, paddle velocity relative to water (v_p) = 0.5200 m/s, power dissipated (P) = 3,069 W.

  4. Step 4 — Substitute the given values:

    A=23069CD996.5vp3A = \dfrac{23069}{C_D996.5 v_p^3}
  5. Step 5 — Evaluate:

    A = 33.1868\ \text{m^2}
  6. Step 6 — Check: returning A = 33.1868 m^2 to

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}

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

Answer:
A = 33.1868\ \text{m^2}

Why the other options are there

  • 66.3736 — kept a factor of two that cancels in the correct rearrangement.
  • 16.5934 — dropped that same factor in the other direction.
  • 36.5055 — rounded an intermediate value before the final step.

Reference: FE Handbook — Reel and Paddle Flocculator

Example 3
Reel and Paddle — solve for paddle velocity relative to water — Reel and Paddle (3)

reel and paddle drag power for a slow-mix flocculator Given drag coefficient of paddle (C_D) = 1.0700; fluid density (rho) = 995.5 kg/m^3; paddle area (A) = 6.4500 m^2; power dissipated (P) = 4,893 W, determine the paddle velocity relative to water (v_p) in m/s.

Given

  • dragcoefficientofpaddle(CD)=1.0700drag coefficient of paddle (C_D) = 1.0700
  • fluiddensity(rho)=995.5kg/m3fluid density (rho) = 995.5 kg/m^3
  • paddlearea(A)=6.4500m2paddle area (A) = 6.4500 m^2
  • powerdissipated(P)=4,893Wpower dissipated (P) = 4,893 W

Find

paddle velocity relative to water (v_p), in m/s

Start with the thinking

  • The governing relation printed in this handbook section is Reel and Paddle.
  • Everything except v_p is given, so isolate v_p 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.
  • Reel and paddle flocculators dissipate power in proportion to paddle drag, area, and relative velocity through the water.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}
  2. Step 2 — Rearrange symbolically for v_p:

    vp=2PCDρA3v_{p} = \sqrt[3]{\dfrac{2P}{C_D\rho A}}
  3. Step 3 — List the givens: drag coefficient of paddle (C_D) = 1.0700, fluid density (rho) = 995.5 kg/m^3, paddle area (A) = 6.4500 m^2, power dissipated (P) = 4,893 W.

  4. Step 4 — Substitute the given values:

    vp=24893CD995.56.45003v_{p} = \sqrt[3]{\dfrac{24893}{C_D995.5 6.4500}}
  5. Step 5 — Evaluate:

    vp=1.1251 m/sv_{p} = 1.1251\ \text{m/s}
  6. Step 6 — Check: returning v_p = 1.1251 m/s to

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}

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

Answer:
vp=1.1251 m/sv_{p} = 1.1251\ \text{m/s}

Why the other options are there

  • 2.2503 — kept a factor of two that cancels in the correct rearrangement.
  • 0.5626 — dropped that same factor in the other direction.
  • 1.2377 — rounded an intermediate value before the final step.

Reference: FE Handbook — Reel and Paddle Flocculator

Example 4
Reel and Paddle — solve for power dissipated (case 2) — Reel and Paddle (4)

reel and paddle flocculator power dissipation calculation Given drag coefficient of paddle (C_D) = 1.4700; fluid density (rho) = 995.0 kg/m^3; paddle area (A) = 1.7000 m^2; paddle velocity relative to water (v_p) = 0.2000 m/s, determine the power dissipated (P) in W.

Given

  • dragcoefficientofpaddle(CD)=1.4700drag coefficient of paddle (C_D) = 1.4700
  • fluiddensity(rho)=995.0kg/m3fluid density (rho) = 995.0 kg/m^3
  • paddlearea(A)=1.7000m2paddle area (A) = 1.7000 m^2
  • paddlevelocityrelativetowater(vp)=0.2000m/spaddle velocity relative to water (v_p) = 0.2000 m/s

Find

power dissipated (P), in W

Start with the thinking

  • The governing relation printed in this handbook section is Reel and Paddle.
  • Everything except P is given, so isolate P 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.
  • Reel and paddle flocculators dissipate power in proportion to paddle drag, area, and relative velocity through the water.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}
  2. Step 2 — Rearrange symbolically for P:

    P=CDρAvp32P = \dfrac{C_D\rho A v_p^3}{2}
  3. Step 3 — List the givens: drag coefficient of paddle (C_D) = 1.4700, fluid density (rho) = 995.0 kg/m^3, paddle area (A) = 1.7000 m^2, paddle velocity relative to water (v_p) = 0.2000 m/s.

  4. Step 4 — Substitute the given values:

    P=CD995.01.7000vp32P = \dfrac{C_D995.0 1.7000 v_p^3}{2}
  5. Step 5 — Evaluate:

    P=9.9460 WP = 9.9460\ \text{W}
  6. Step 6 — Check: returning P = 9.9460 W to

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}

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

Answer:
P=9.9460 WP = 9.9460\ \text{W}

Why the other options are there

  • 19.8920 — kept a factor of two that cancels in the correct rearrangement.
  • 4.9730 — dropped that same factor in the other direction.
  • 10.9406 — rounded an intermediate value before the final step.

Reference: FE Handbook — Reel and Paddle Flocculator

Example 5
Reel and Paddle — solve for paddle area (case 2) — Reel and Paddle (5)

reel and paddle mixer design for flocculation basin Given drag coefficient of paddle (C_D) = 1.2000; fluid density (rho) = 996.0 kg/m^3; paddle velocity relative to water (v_p) = 0.4400 m/s; power dissipated (P) = 1,915 W, determine the paddle area (A) in m^2.

Given

  • dragcoefficientofpaddle(CD)=1.2000drag coefficient of paddle (C_D) = 1.2000
  • fluiddensity(rho)=996.0kg/m3fluid density (rho) = 996.0 kg/m^3
  • paddlevelocityrelativetowater(vp)=0.4400m/spaddle velocity relative to water (v_p) = 0.4400 m/s
  • powerdissipated(P)=1,915Wpower dissipated (P) = 1,915 W

Find

paddle area (A), in m^2

Start with the thinking

  • The governing relation printed in this handbook section is Reel and Paddle.
  • Everything except A is given, so isolate A 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.
  • Reel and paddle flocculators dissipate power in proportion to paddle drag, area, and relative velocity through the water.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}
  2. Step 2 — Rearrange symbolically for A:

    A=2PCDρvp3A = \dfrac{2P}{C_D\rho v_p^3}
  3. Step 3 — List the givens: drag coefficient of paddle (C_D) = 1.2000, fluid density (rho) = 996.0 kg/m^3, paddle velocity relative to water (v_p) = 0.4400 m/s, power dissipated (P) = 1,915 W.

  4. Step 4 — Substitute the given values:

    A=21915CD996.0vp3A = \dfrac{21915}{C_D996.0 v_p^3}
  5. Step 5 — Evaluate:

    A = 37.6184\ \text{m^2}
  6. Step 6 — Check: returning A = 37.6184 m^2 to

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}

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

Answer:
A = 37.6184\ \text{m^2}

Why the other options are there

  • 75.2368 — kept a factor of two that cancels in the correct rearrangement.
  • 18.8092 — dropped that same factor in the other direction.
  • 41.3802 — rounded an intermediate value before the final step.

Reference: FE Handbook — Reel and Paddle Flocculator

Example 6
Reel and Paddle — solve for paddle velocity relative to water (case 2) — Reel and Paddle (6)

reel and paddle drag power for a slow-mix flocculator Given drag coefficient of paddle (C_D) = 1.9900; fluid density (rho) = 998.0 kg/m^3; paddle area (A) = 4.0500 m^2; power dissipated (P) = 1,199 W, determine the paddle velocity relative to water (v_p) in m/s.

Given

  • dragcoefficientofpaddle(CD)=1.9900drag coefficient of paddle (C_D) = 1.9900
  • fluiddensity(rho)=998.0kg/m3fluid density (rho) = 998.0 kg/m^3
  • paddlearea(A)=4.0500m2paddle area (A) = 4.0500 m^2
  • powerdissipated(P)=1,199Wpower dissipated (P) = 1,199 W

Find

paddle velocity relative to water (v_p), in m/s

Start with the thinking

  • The governing relation printed in this handbook section is Reel and Paddle.
  • Everything except v_p is given, so isolate v_p 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.
  • Reel and paddle flocculators dissipate power in proportion to paddle drag, area, and relative velocity through the water.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}
  2. Step 2 — Rearrange symbolically for v_p:

    vp=2PCDρA3v_{p} = \sqrt[3]{\dfrac{2P}{C_D\rho A}}
  3. Step 3 — List the givens: drag coefficient of paddle (C_D) = 1.9900, fluid density (rho) = 998.0 kg/m^3, paddle area (A) = 4.0500 m^2, power dissipated (P) = 1,199 W.

  4. Step 4 — Substitute the given values:

    vp=21199CD998.04.05003v_{p} = \sqrt[3]{\dfrac{21199}{C_D998.0 4.0500}}
  5. Step 5 — Evaluate:

    vp=0.6680 m/sv_{p} = 0.6680\ \text{m/s}
  6. Step 6 — Check: returning v_p = 0.6680 m/s to

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}

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

Answer:
vp=0.6680 m/sv_{p} = 0.6680\ \text{m/s}

Why the other options are there

  • 1.3361 — kept a factor of two that cancels in the correct rearrangement.
  • 0.3340 — dropped that same factor in the other direction.
  • 0.7348 — rounded an intermediate value before the final step.

Reference: FE Handbook — Reel and Paddle Flocculator

Example 7
Reel and Paddle — solve for power dissipated (case 3) — Reel and Paddle (7)

reel and paddle flocculator power dissipation calculation Given drag coefficient of paddle (C_D) = 1.8600; fluid density (rho) = 998.5 kg/m^3; paddle area (A) = 3.0000 m^2; paddle velocity relative to water (v_p) = 0.2500 m/s, determine the power dissipated (P) in W.

Given

  • dragcoefficientofpaddle(CD)=1.8600drag coefficient of paddle (C_D) = 1.8600
  • fluiddensity(rho)=998.5kg/m3fluid density (rho) = 998.5 kg/m^3
  • paddlearea(A)=3.0000m2paddle area (A) = 3.0000 m^2
  • paddlevelocityrelativetowater(vp)=0.2500m/spaddle velocity relative to water (v_p) = 0.2500 m/s

Find

power dissipated (P), in W

Start with the thinking

  • The governing relation printed in this handbook section is Reel and Paddle.
  • Everything except P is given, so isolate P 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.
  • Reel and paddle flocculators dissipate power in proportion to paddle drag, area, and relative velocity through the water.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}
  2. Step 2 — Rearrange symbolically for P:

    P=CDρAvp32P = \dfrac{C_D\rho A v_p^3}{2}
  3. Step 3 — List the givens: drag coefficient of paddle (C_D) = 1.8600, fluid density (rho) = 998.5 kg/m^3, paddle area (A) = 3.0000 m^2, paddle velocity relative to water (v_p) = 0.2500 m/s.

  4. Step 4 — Substitute the given values:

    P=CD998.53.0000vp32P = \dfrac{C_D998.5 3.0000 v_p^3}{2}
  5. Step 5 — Evaluate:

    P=43.5284 WP = 43.5284\ \text{W}
  6. Step 6 — Check: returning P = 43.5284 W to

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}

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

Answer:
P=43.5284 WP = 43.5284\ \text{W}

Why the other options are there

  • 87.0567 — kept a factor of two that cancels in the correct rearrangement.
  • 21.7642 — dropped that same factor in the other direction.
  • 47.8812 — rounded an intermediate value before the final step.

Reference: FE Handbook — Reel and Paddle Flocculator

Example 8
Reel and Paddle — solve for paddle area (case 3) — Reel and Paddle (8)

reel and paddle mixer design for flocculation basin Given drag coefficient of paddle (C_D) = 1.8400; fluid density (rho) = 994.5 kg/m^3; paddle velocity relative to water (v_p) = 0.8100 m/s; power dissipated (P) = 1,679 W, determine the paddle area (A) in m^2.

Given

  • dragcoefficientofpaddle(CD)=1.8400drag coefficient of paddle (C_D) = 1.8400
  • fluiddensity(rho)=994.5kg/m3fluid density (rho) = 994.5 kg/m^3
  • paddlevelocityrelativetowater(vp)=0.8100m/spaddle velocity relative to water (v_p) = 0.8100 m/s
  • powerdissipated(P)=1,679Wpower dissipated (P) = 1,679 W

Find

paddle area (A), in m^2

Start with the thinking

  • The governing relation printed in this handbook section is Reel and Paddle.
  • Everything except A is given, so isolate A 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.
  • Reel and paddle flocculators dissipate power in proportion to paddle drag, area, and relative velocity through the water.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}
  2. Step 2 — Rearrange symbolically for A:

    A=2PCDρvp3A = \dfrac{2P}{C_D\rho v_p^3}
  3. Step 3 — List the givens: drag coefficient of paddle (C_D) = 1.8400, fluid density (rho) = 994.5 kg/m^3, paddle velocity relative to water (v_p) = 0.8100 m/s, power dissipated (P) = 1,679 W.

  4. Step 4 — Substitute the given values:

    A=21679CD994.5vp3A = \dfrac{21679}{C_D994.5 v_p^3}
  5. Step 5 — Evaluate:

    A = 3.4531\ \text{m^2}
  6. Step 6 — Check: returning A = 3.4531 m^2 to

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}

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

Answer:
A = 3.4531\ \text{m^2}

Why the other options are there

  • 6.9061 — kept a factor of two that cancels in the correct rearrangement.
  • 1.7265 — dropped that same factor in the other direction.
  • 3.7984 — rounded an intermediate value before the final step.

Reference: FE Handbook — Reel and Paddle Flocculator

Example 9
Reel and Paddle — solve for paddle velocity relative to water (case 3) — Reel and Paddle (9)

reel and paddle drag power for a slow-mix flocculator Given drag coefficient of paddle (C_D) = 1.0500; fluid density (rho) = 998.0 kg/m^3; paddle area (A) = 0.9000 m^2; power dissipated (P) = 4,091 W, determine the paddle velocity relative to water (v_p) in m/s.

Given

  • dragcoefficientofpaddle(CD)=1.0500drag coefficient of paddle (C_D) = 1.0500
  • fluiddensity(rho)=998.0kg/m3fluid density (rho) = 998.0 kg/m^3
  • paddlearea(A)=0.9000m2paddle area (A) = 0.9000 m^2
  • powerdissipated(P)=4,091Wpower dissipated (P) = 4,091 W

Find

paddle velocity relative to water (v_p), in m/s

Start with the thinking

  • The governing relation printed in this handbook section is Reel and Paddle.
  • Everything except v_p is given, so isolate v_p 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.
  • Reel and paddle flocculators dissipate power in proportion to paddle drag, area, and relative velocity through the water.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}
  2. Step 2 — Rearrange symbolically for v_p:

    vp=2PCDρA3v_{p} = \sqrt[3]{\dfrac{2P}{C_D\rho A}}
  3. Step 3 — List the givens: drag coefficient of paddle (C_D) = 1.0500, fluid density (rho) = 998.0 kg/m^3, paddle area (A) = 0.9000 m^2, power dissipated (P) = 4,091 W.

  4. Step 4 — Substitute the given values:

    vp=24091CD998.00.90003v_{p} = \sqrt[3]{\dfrac{24091}{C_D998.0 0.9000}}
  5. Step 5 — Evaluate:

    vp=2.0548 m/sv_{p} = 2.0548\ \text{m/s}
  6. Step 6 — Check: returning v_p = 2.0548 m/s to

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}

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

Answer:
vp=2.0548 m/sv_{p} = 2.0548\ \text{m/s}

Why the other options are there

  • 4.1096 — kept a factor of two that cancels in the correct rearrangement.
  • 1.0274 — dropped that same factor in the other direction.
  • 2.2603 — rounded an intermediate value before the final step.

Reference: FE Handbook — Reel and Paddle Flocculator

Example 10
Reel and Paddle — solve for power dissipated (case 4) — Reel and Paddle (10)

reel and paddle flocculator power dissipation calculation Given drag coefficient of paddle (C_D) = 1.7700; fluid density (rho) = 992.5 kg/m^3; paddle area (A) = 6.0000 m^2; paddle velocity relative to water (v_p) = 0.4500 m/s, determine the power dissipated (P) in W.

Given

  • dragcoefficientofpaddle(CD)=1.7700drag coefficient of paddle (C_D) = 1.7700
  • fluiddensity(rho)=992.5kg/m3fluid density (rho) = 992.5 kg/m^3
  • paddlearea(A)=6.0000m2paddle area (A) = 6.0000 m^2
  • paddlevelocityrelativetowater(vp)=0.4500m/spaddle velocity relative to water (v_p) = 0.4500 m/s

Find

power dissipated (P), in W

Start with the thinking

  • The governing relation printed in this handbook section is Reel and Paddle.
  • Everything except P is given, so isolate P 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.
  • Reel and paddle flocculators dissipate power in proportion to paddle drag, area, and relative velocity through the water.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}
  2. Step 2 — Rearrange symbolically for P:

    P=CDρAvp32P = \dfrac{C_D\rho A v_p^3}{2}
  3. Step 3 — List the givens: drag coefficient of paddle (C_D) = 1.7700, fluid density (rho) = 992.5 kg/m^3, paddle area (A) = 6.0000 m^2, paddle velocity relative to water (v_p) = 0.4500 m/s.

  4. Step 4 — Substitute the given values:

    P=CD992.56.0000vp32P = \dfrac{C_D992.5 6.0000 v_p^3}{2}
  5. Step 5 — Evaluate:

    P=480.2 WP = 480.2\ \text{W}
  6. Step 6 — Check: returning P = 480.2 W to

    P=CDρAvp32P = C_D \rho A \dfrac{v_p^3}{2}

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

Answer:
P=480.2 WP = 480.2\ \text{W}

Why the other options are there

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

Reference: FE Handbook — Reel and Paddle Flocculator

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