Absolute viscosity, µ
Environmental Engineering · FE Reference Handbook section
Core formulas for this FE topic
Definitions, applicability, units, assumptions and worked examples for each relation.
This section is conceptual; there are no equations to memorise.
Worked exam-style examples
The four ways this section is written on the real exam — thoughts first, then equations, then substitution.
absolute viscosity of water used in settling velocity calculations Given kinematic viscosity (nu) = 0.0000 m^2/s; density (rho) = 997.1 kg/m^3, determine the absolute viscosity (mu) in Pa*s.
Given
Find
absolute viscosity (mu), in Pa*s
Start with the thinking
- The governing relation printed in this handbook section is Absolute viscosity.
- Everything except mu is given, so isolate mu 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.
- Absolute viscosity relates dynamic and kinematic viscosity of water through fluid density for environmental flow calculations.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for mu:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning mu = 0.0010 Pa*s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0020 — kept a factor of two that cancels in the correct rearrangement.
- 0.0005 — dropped that same factor in the other direction.
- 0.0011 — rounded an intermediate value before the final step.
Reference: FE Handbook — Absolute (Dynamic) Viscosity
absolute viscosity determined from kinematic viscosity and density at plant temperature Given density (rho) = 992.4 kg/m^3; absolute viscosity (mu) = 0.0014 Pa*s, determine the kinematic viscosity (nu) in m^2/s.
Given
Find
kinematic viscosity (nu), in m^2/s
Start with the thinking
- The governing relation printed in this handbook section is Absolute viscosity.
- Everything except nu is given, so isolate nu 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.
- Absolute viscosity relates dynamic and kinematic viscosity of water through fluid density for environmental flow calculations.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for nu:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
\nu = 0.0000\ \text{m^2/s}Step 6 — Check: returning nu = 0.0000 m^2/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0000 — kept a factor of two that cancels in the correct rearrangement.
- 0.0000 — dropped that same factor in the other direction.
- 0.0000 — rounded an intermediate value before the final step.
Reference: FE Handbook — Absolute (Dynamic) Viscosity
absolute viscosity of wastewater at treatment plant operating temperature Given kinematic viscosity (nu) = 0.0000 m^2/s; absolute viscosity (mu) = 0.0015 Pa*s, determine the density (rho) in kg/m^3.
Given
Find
density (rho), in kg/m^3
Start with the thinking
- The governing relation printed in this handbook section is Absolute viscosity.
- Everything except rho is given, so isolate rho 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.
- Absolute viscosity relates dynamic and kinematic viscosity of water through fluid density for environmental flow calculations.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for rho:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
\rho = 1540\ \text{kg/m^3}Step 6 — Check: returning rho = 1,540 kg/m^3 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 3,080 — kept a factor of two that cancels in the correct rearrangement.
- 770.0 — dropped that same factor in the other direction.
- 1,694 — rounded an intermediate value before the final step.
Reference: FE Handbook — Absolute (Dynamic) Viscosity
absolute viscosity of water used in settling velocity calculations Given kinematic viscosity (nu) = 0.0000 m^2/s; density (rho) = 996.4 kg/m^3, determine the absolute viscosity (mu) in Pa*s.
Given
Find
absolute viscosity (mu), in Pa*s
Start with the thinking
- The governing relation printed in this handbook section is Absolute viscosity.
- Everything except mu is given, so isolate mu 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.
- Absolute viscosity relates dynamic and kinematic viscosity of water through fluid density for environmental flow calculations.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for mu:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning mu = 0.0010 Pa*s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0020 — kept a factor of two that cancels in the correct rearrangement.
- 0.0005 — dropped that same factor in the other direction.
- 0.0011 — rounded an intermediate value before the final step.
Reference: FE Handbook — Absolute (Dynamic) Viscosity
absolute viscosity determined from kinematic viscosity and density at plant temperature Given density (rho) = 992.7 kg/m^3; absolute viscosity (mu) = 0.0017 Pa*s, determine the kinematic viscosity (nu) in m^2/s.
Given
Find
kinematic viscosity (nu), in m^2/s
Start with the thinking
- The governing relation printed in this handbook section is Absolute viscosity.
- Everything except nu is given, so isolate nu 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.
- Absolute viscosity relates dynamic and kinematic viscosity of water through fluid density for environmental flow calculations.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for nu:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
\nu = 0.0000\ \text{m^2/s}Step 6 — Check: returning nu = 0.0000 m^2/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0000 — kept a factor of two that cancels in the correct rearrangement.
- 0.0000 — dropped that same factor in the other direction.
- 0.0000 — rounded an intermediate value before the final step.
Reference: FE Handbook — Absolute (Dynamic) Viscosity
absolute viscosity of wastewater at treatment plant operating temperature Given kinematic viscosity (nu) = 0.0000 m^2/s; absolute viscosity (mu) = 0.0014 Pa*s, determine the density (rho) in kg/m^3.
Given
Find
density (rho), in kg/m^3
Start with the thinking
- The governing relation printed in this handbook section is Absolute viscosity.
- Everything except rho is given, so isolate rho 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.
- Absolute viscosity relates dynamic and kinematic viscosity of water through fluid density for environmental flow calculations.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for rho:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
\rho = 695.0\ \text{kg/m^3}Step 6 — Check: returning rho = 695.0 kg/m^3 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 1,390 — kept a factor of two that cancels in the correct rearrangement.
- 347.5 — dropped that same factor in the other direction.
- 764.5 — rounded an intermediate value before the final step.
Reference: FE Handbook — Absolute (Dynamic) Viscosity
absolute viscosity of water used in settling velocity calculations Given kinematic viscosity (nu) = 0.0000 m^2/s; density (rho) = 995.7 kg/m^3, determine the absolute viscosity (mu) in Pa*s.
Given
Find
absolute viscosity (mu), in Pa*s
Start with the thinking
- The governing relation printed in this handbook section is Absolute viscosity.
- Everything except mu is given, so isolate mu 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.
- Absolute viscosity relates dynamic and kinematic viscosity of water through fluid density for environmental flow calculations.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for mu:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning mu = 0.0010 Pa*s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0020 — kept a factor of two that cancels in the correct rearrangement.
- 0.0005 — dropped that same factor in the other direction.
- 0.0011 — rounded an intermediate value before the final step.
Reference: FE Handbook — Absolute (Dynamic) Viscosity
absolute viscosity determined from kinematic viscosity and density at plant temperature Given density (rho) = 990.5 kg/m^3; absolute viscosity (mu) = 0.0010 Pa*s, determine the kinematic viscosity (nu) in m^2/s.
Given
Find
kinematic viscosity (nu), in m^2/s
Start with the thinking
- The governing relation printed in this handbook section is Absolute viscosity.
- Everything except nu is given, so isolate nu 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.
- Absolute viscosity relates dynamic and kinematic viscosity of water through fluid density for environmental flow calculations.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for nu:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
\nu = 0.0000\ \text{m^2/s}Step 6 — Check: returning nu = 0.0000 m^2/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0000 — kept a factor of two that cancels in the correct rearrangement.
- 0.0000 — dropped that same factor in the other direction.
- 0.0000 — rounded an intermediate value before the final step.
Reference: FE Handbook — Absolute (Dynamic) Viscosity
absolute viscosity of wastewater at treatment plant operating temperature Given kinematic viscosity (nu) = 0.0000 m^2/s; absolute viscosity (mu) = 0.0012 Pa*s, determine the density (rho) in kg/m^3.
Given
Find
density (rho), in kg/m^3
Start with the thinking
- The governing relation printed in this handbook section is Absolute viscosity.
- Everything except rho is given, so isolate rho 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.
- Absolute viscosity relates dynamic and kinematic viscosity of water through fluid density for environmental flow calculations.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for rho:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
\rho = 1220\ \text{kg/m^3}Step 6 — Check: returning rho = 1,220 kg/m^3 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 2,440 — kept a factor of two that cancels in the correct rearrangement.
- 610.0 — dropped that same factor in the other direction.
- 1,342 — rounded an intermediate value before the final step.
Reference: FE Handbook — Absolute (Dynamic) Viscosity
absolute viscosity of water used in settling velocity calculations Given kinematic viscosity (nu) = 0.0000 m^2/s; density (rho) = 996.8 kg/m^3, determine the absolute viscosity (mu) in Pa*s.
Given
Find
absolute viscosity (mu), in Pa*s
Start with the thinking
- The governing relation printed in this handbook section is Absolute viscosity.
- Everything except mu is given, so isolate mu 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.
- Absolute viscosity relates dynamic and kinematic viscosity of water through fluid density for environmental flow calculations.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for mu:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning mu = 0.0020 Pa*s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0040 — kept a factor of two that cancels in the correct rearrangement.
- 0.0010 — dropped that same factor in the other direction.
- 0.0022 — rounded an intermediate value before the final step.
Reference: FE Handbook — Absolute (Dynamic) Viscosity