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Surface Tension and Capillarity

Fluid Mechanics · FE Reference Handbook section

Fluid Mechanics
10 formulas
10 exam-style examples
~60 min
All Fluid Mechanics lectures

Handbook notes for this section

Definitions and conditions exactly as the handbook states them.

  • The capillary rise h is approximated by

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
Surface tension and capillarity (capillary rise) — solve for capillary rise — Surface Tension and Capillarity

surface tension and capillarity in a water-filled capillary tube Given surface tension (sigma) = 0.0390 N/m; wetting angle (theta) = 29.0000 deg; specific weight (gamma) = 9,020 N/m^3; tube diameter (d) = 0.0045 m, determine the capillary rise (h) in m.

Given

  • surfacetension(sigma)=0.0390N/msurface tension (sigma) = 0.0390 N/m
  • wettingangle(theta)=29.0000degwetting angle (theta) = 29.0000 deg
  • specificweight(gamma)=9,020N/m3specific weight (gamma) = 9,020 N/m^3
  • tubediameter(d)=0.0045mtube diameter (d) = 0.0045 m

Find

capillary rise (h), in m

Start with the thinking

  • The governing relation printed in this handbook section is Surface tension and capillarity (capillary rise).
  • Everything except h is given, so isolate h 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.
  • A capillary tube experiment illustrates surface tension and capillarity in a small-diameter glass tube.
h = capillary rise

Figure 1 — schematic for Surface tension and capillarity (capillary rise) — solve for capillary rise — Surface Tension and Capillarity

Step-by-step solution

  1. Step 1 — State the governing relation:

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}
  2. Step 2 — Rearrange the relation so that h stands alone on the left-hand side.

  3. Step 3 — List the givens: surface tension (sigma) = 0.0390 N/m, wetting angle (theta) = 29.0000 deg, specific weight (gamma) = 9,020 N/m^3, tube diameter (d) = 0.0045 m.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    h=0.0034 mh = 0.0034\ \text{m}
  6. Step 6 — Check: returning h = 0.0034 m to

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}

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

Answer:
h=0.0034 mh = 0.0034\ \text{m}

Why the other options are there

  • 0.0067 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0017 — dropped that same factor in the other direction.
  • 0.0037 — rounded an intermediate value before the final step.

Reference: FE Handbook — Surface Tension and Capillarity

Example 2
Surface tension and capillarity (capillary rise) — solve for surface tension — Surface Tension and Capillarity (2)

surface tension and capillarity of mercury in a glass tube Given wetting angle (theta) = 35.0000 deg; specific weight (gamma) = 9,070 N/m^3; tube diameter (d) = 0.0096 m; capillary rise (h) = 0.0030 m, determine the surface tension (sigma) in N/m.

Given

  • wettingangle(theta)=35.0000degwetting angle (theta) = 35.0000 deg
  • specificweight(gamma)=9,070N/m3specific weight (gamma) = 9,070 N/m^3
  • tubediameter(d)=0.0096mtube diameter (d) = 0.0096 m
  • capillaryrise(h)=0.0030mcapillary rise (h) = 0.0030 m

Find

surface tension (sigma), in N/m

Start with the thinking

  • The governing relation printed in this handbook section is Surface tension and capillarity (capillary rise).
  • Everything except sigma is given, so isolate sigma 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.
  • A capillary tube experiment illustrates surface tension and capillarity in a small-diameter glass tube.
h = capillary rise

Figure 2 — schematic for Surface tension and capillarity (capillary rise) — solve for surface tension — Surface Tension and Capillarity (2)

Step-by-step solution

  1. Step 1 — State the governing relation:

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}
  2. Step 2 — Rearrange the relation so that sigma stands alone on the left-hand side.

  3. Step 3 — List the givens: wetting angle (theta) = 35.0000 deg, specific weight (gamma) = 9,070 N/m^3, tube diameter (d) = 0.0096 m, capillary rise (h) = 0.0030 m.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    σ=0.0797 N/m\sigma = 0.0797\ \text{N/m}
  6. Step 6 — Check: returning sigma = 0.0797 N/m to

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}

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

Answer:
σ=0.0797 N/m\sigma = 0.0797\ \text{N/m}

Why the other options are there

  • 0.1594 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0399 — dropped that same factor in the other direction.
  • 0.0877 — rounded an intermediate value before the final step.

Reference: FE Handbook — Surface Tension and Capillarity

Example 3
Surface tension and capillarity (capillary rise) — solve for tube diameter — Surface Tension and Capillarity (3)

capillarity effects on a manometer reading due to surface tension Given surface tension (sigma) = 0.0650 N/m; wetting angle (theta) = 9.0000 deg; specific weight (gamma) = 9,380 N/m^3; capillary rise (h) = 0.0150 m, determine the tube diameter (d) in m.

Given

  • surfacetension(sigma)=0.0650N/msurface tension (sigma) = 0.0650 N/m
  • wettingangle(theta)=9.0000degwetting angle (theta) = 9.0000 deg
  • specificweight(gamma)=9,380N/m3specific weight (gamma) = 9,380 N/m^3
  • capillaryrise(h)=0.0150mcapillary rise (h) = 0.0150 m

Find

tube diameter (d), in m

Start with the thinking

  • The governing relation printed in this handbook section is Surface tension and capillarity (capillary rise).
  • Everything except d is given, so isolate d 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.
  • A capillary tube experiment illustrates surface tension and capillarity in a small-diameter glass tube.
h = capillary rise

Figure 3 — schematic for Surface tension and capillarity (capillary rise) — solve for tube diameter — Surface Tension and Capillarity (3)

Step-by-step solution

  1. Step 1 — State the governing relation:

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}
  2. Step 2 — Rearrange the relation so that d stands alone on the left-hand side.

  3. Step 3 — List the givens: surface tension (sigma) = 0.0650 N/m, wetting angle (theta) = 9.0000 deg, specific weight (gamma) = 9,380 N/m^3, capillary rise (h) = 0.0150 m.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    d=0.0018 md = 0.0018\ \text{m}
  6. Step 6 — Check: returning d = 0.0018 m to

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}

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

Answer:
d=0.0018 md = 0.0018\ \text{m}

Why the other options are there

  • 0.0037 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0009 — dropped that same factor in the other direction.
  • 0.0020 — rounded an intermediate value before the final step.

Reference: FE Handbook — Surface Tension and Capillarity

Example 4
Surface tension and capillarity (capillary rise) — solve for capillary rise (case 2) — Surface Tension and Capillarity (4)

surface tension and capillarity in a water-filled capillary tube Given surface tension (sigma) = 0.0470 N/m; wetting angle (theta) = 9.0000 deg; specific weight (gamma) = 9,580 N/m^3; tube diameter (d) = 0.0062 m, determine the capillary rise (h) in m.

Given

  • surfacetension(sigma)=0.0470N/msurface tension (sigma) = 0.0470 N/m
  • wettingangle(theta)=9.0000degwetting angle (theta) = 9.0000 deg
  • specificweight(gamma)=9,580N/m3specific weight (gamma) = 9,580 N/m^3
  • tubediameter(d)=0.0062mtube diameter (d) = 0.0062 m

Find

capillary rise (h), in m

Start with the thinking

  • The governing relation printed in this handbook section is Surface tension and capillarity (capillary rise).
  • Everything except h is given, so isolate h 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.
  • A capillary tube experiment illustrates surface tension and capillarity in a small-diameter glass tube.
h = capillary rise

Figure 4 — schematic for Surface tension and capillarity (capillary rise) — solve for capillary rise (case 2) — Surface Tension and Capillarity (4)

Step-by-step solution

  1. Step 1 — State the governing relation:

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}
  2. Step 2 — Rearrange the relation so that h stands alone on the left-hand side.

  3. Step 3 — List the givens: surface tension (sigma) = 0.0470 N/m, wetting angle (theta) = 9.0000 deg, specific weight (gamma) = 9,580 N/m^3, tube diameter (d) = 0.0062 m.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    h=0.0031 mh = 0.0031\ \text{m}
  6. Step 6 — Check: returning h = 0.0031 m to

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}

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

Answer:
h=0.0031 mh = 0.0031\ \text{m}

Why the other options are there

  • 0.0063 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0016 — dropped that same factor in the other direction.
  • 0.0034 — rounded an intermediate value before the final step.

Reference: FE Handbook — Surface Tension and Capillarity

Example 5
Surface tension and capillarity (capillary rise) — solve for surface tension (case 2) — Surface Tension and Capillarity (5)

surface tension and capillarity of mercury in a glass tube Given wetting angle (theta) = 15.0000 deg; specific weight (gamma) = 9,300 N/m^3; tube diameter (d) = 0.0025 m; capillary rise (h) = 0.0540 m, determine the surface tension (sigma) in N/m.

Given

  • wettingangle(theta)=15.0000degwetting angle (theta) = 15.0000 deg
  • specificweight(gamma)=9,300N/m3specific weight (gamma) = 9,300 N/m^3
  • tubediameter(d)=0.0025mtube diameter (d) = 0.0025 m
  • capillaryrise(h)=0.0540mcapillary rise (h) = 0.0540 m

Find

surface tension (sigma), in N/m

Start with the thinking

  • The governing relation printed in this handbook section is Surface tension and capillarity (capillary rise).
  • Everything except sigma is given, so isolate sigma 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.
  • A capillary tube experiment illustrates surface tension and capillarity in a small-diameter glass tube.
h = capillary rise

Figure 5 — schematic for Surface tension and capillarity (capillary rise) — solve for surface tension (case 2) — Surface Tension and Capillarity (5)

Step-by-step solution

  1. Step 1 — State the governing relation:

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}
  2. Step 2 — Rearrange the relation so that sigma stands alone on the left-hand side.

  3. Step 3 — List the givens: wetting angle (theta) = 15.0000 deg, specific weight (gamma) = 9,300 N/m^3, tube diameter (d) = 0.0025 m, capillary rise (h) = 0.0540 m.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    σ=0.3249 N/m\sigma = 0.3249\ \text{N/m}
  6. Step 6 — Check: returning sigma = 0.3249 N/m to

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}

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

Answer:
σ=0.3249 N/m\sigma = 0.3249\ \text{N/m}

Why the other options are there

  • 0.6499 — kept a factor of two that cancels in the correct rearrangement.
  • 0.1625 — dropped that same factor in the other direction.
  • 0.3574 — rounded an intermediate value before the final step.

Reference: FE Handbook — Surface Tension and Capillarity

Example 6
Surface tension and capillarity (capillary rise) — solve for tube diameter (case 2) — Surface Tension and Capillarity (6)

capillarity effects on a manometer reading due to surface tension Given surface tension (sigma) = 0.0710 N/m; wetting angle (theta) = 33.0000 deg; specific weight (gamma) = 9,270 N/m^3; capillary rise (h) = 0.0465 m, determine the tube diameter (d) in m.

Given

  • surfacetension(sigma)=0.0710N/msurface tension (sigma) = 0.0710 N/m
  • wettingangle(theta)=33.0000degwetting angle (theta) = 33.0000 deg
  • specificweight(gamma)=9,270N/m3specific weight (gamma) = 9,270 N/m^3
  • capillaryrise(h)=0.0465mcapillary rise (h) = 0.0465 m

Find

tube diameter (d), in m

Start with the thinking

  • The governing relation printed in this handbook section is Surface tension and capillarity (capillary rise).
  • Everything except d is given, so isolate d 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.
  • A capillary tube experiment illustrates surface tension and capillarity in a small-diameter glass tube.
h = capillary rise

Figure 6 — schematic for Surface tension and capillarity (capillary rise) — solve for tube diameter (case 2) — Surface Tension and Capillarity (6)

Step-by-step solution

  1. Step 1 — State the governing relation:

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}
  2. Step 2 — Rearrange the relation so that d stands alone on the left-hand side.

  3. Step 3 — List the givens: surface tension (sigma) = 0.0710 N/m, wetting angle (theta) = 33.0000 deg, specific weight (gamma) = 9,270 N/m^3, capillary rise (h) = 0.0465 m.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    d=0.0006 md = 0.0006\ \text{m}
  6. Step 6 — Check: returning d = 0.0006 m to

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}

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

Answer:
d=0.0006 md = 0.0006\ \text{m}

Why the other options are there

  • 0.0011 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0003 — dropped that same factor in the other direction.
  • 0.0006 — rounded an intermediate value before the final step.

Reference: FE Handbook — Surface Tension and Capillarity

Example 7
Surface tension and capillarity (capillary rise) — solve for capillary rise (case 3) — Surface Tension and Capillarity (7)

surface tension and capillarity in a water-filled capillary tube Given surface tension (sigma) = 0.0560 N/m; wetting angle (theta) = 7.0000 deg; specific weight (gamma) = 9,610 N/m^3; tube diameter (d) = 0.0041 m, determine the capillary rise (h) in m.

Given

  • surfacetension(sigma)=0.0560N/msurface tension (sigma) = 0.0560 N/m
  • wettingangle(theta)=7.0000degwetting angle (theta) = 7.0000 deg
  • specificweight(gamma)=9,610N/m3specific weight (gamma) = 9,610 N/m^3
  • tubediameter(d)=0.0041mtube diameter (d) = 0.0041 m

Find

capillary rise (h), in m

Start with the thinking

  • The governing relation printed in this handbook section is Surface tension and capillarity (capillary rise).
  • Everything except h is given, so isolate h 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.
  • A capillary tube experiment illustrates surface tension and capillarity in a small-diameter glass tube.
h = capillary rise

Figure 7 — schematic for Surface tension and capillarity (capillary rise) — solve for capillary rise (case 3) — Surface Tension and Capillarity (7)

Step-by-step solution

  1. Step 1 — State the governing relation:

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}
  2. Step 2 — Rearrange the relation so that h stands alone on the left-hand side.

  3. Step 3 — List the givens: surface tension (sigma) = 0.0560 N/m, wetting angle (theta) = 7.0000 deg, specific weight (gamma) = 9,610 N/m^3, tube diameter (d) = 0.0041 m.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    h=0.0056 mh = 0.0056\ \text{m}
  6. Step 6 — Check: returning h = 0.0056 m to

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}

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

Answer:
h=0.0056 mh = 0.0056\ \text{m}

Why the other options are there

  • 0.0113 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0028 — dropped that same factor in the other direction.
  • 0.0062 — rounded an intermediate value before the final step.

Reference: FE Handbook — Surface Tension and Capillarity

Example 8
Surface tension and capillarity (capillary rise) — solve for surface tension (case 3) — Surface Tension and Capillarity (8)

surface tension and capillarity of mercury in a glass tube Given wetting angle (theta) = 34.0000 deg; specific weight (gamma) = 9,560 N/m^3; tube diameter (d) = 0.0025 m; capillary rise (h) = 0.0510 m, determine the surface tension (sigma) in N/m.

Given

  • wettingangle(theta)=34.0000degwetting angle (theta) = 34.0000 deg
  • specificweight(gamma)=9,560N/m3specific weight (gamma) = 9,560 N/m^3
  • tubediameter(d)=0.0025mtube diameter (d) = 0.0025 m
  • capillaryrise(h)=0.0510mcapillary rise (h) = 0.0510 m

Find

surface tension (sigma), in N/m

Start with the thinking

  • The governing relation printed in this handbook section is Surface tension and capillarity (capillary rise).
  • Everything except sigma is given, so isolate sigma 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.
  • A capillary tube experiment illustrates surface tension and capillarity in a small-diameter glass tube.
h = capillary rise

Figure 8 — schematic for Surface tension and capillarity (capillary rise) — solve for surface tension (case 3) — Surface Tension and Capillarity (8)

Step-by-step solution

  1. Step 1 — State the governing relation:

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}
  2. Step 2 — Rearrange the relation so that sigma stands alone on the left-hand side.

  3. Step 3 — List the givens: wetting angle (theta) = 34.0000 deg, specific weight (gamma) = 9,560 N/m^3, tube diameter (d) = 0.0025 m, capillary rise (h) = 0.0510 m.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    σ=0.3676 N/m\sigma = 0.3676\ \text{N/m}
  6. Step 6 — Check: returning sigma = 0.3676 N/m to

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}

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

Answer:
σ=0.3676 N/m\sigma = 0.3676\ \text{N/m}

Why the other options are there

  • 0.7351 — kept a factor of two that cancels in the correct rearrangement.
  • 0.1838 — dropped that same factor in the other direction.
  • 0.4043 — rounded an intermediate value before the final step.

Reference: FE Handbook — Surface Tension and Capillarity

Example 9
Surface tension and capillarity (capillary rise) — solve for tube diameter (case 3) — Surface Tension and Capillarity (9)

capillarity effects on a manometer reading due to surface tension Given surface tension (sigma) = 0.0730 N/m; wetting angle (theta) = 36.0000 deg; specific weight (gamma) = 9,310 N/m^3; capillary rise (h) = 0.0260 m, determine the tube diameter (d) in m.

Given

  • surfacetension(sigma)=0.0730N/msurface tension (sigma) = 0.0730 N/m
  • wettingangle(theta)=36.0000degwetting angle (theta) = 36.0000 deg
  • specificweight(gamma)=9,310N/m3specific weight (gamma) = 9,310 N/m^3
  • capillaryrise(h)=0.0260mcapillary rise (h) = 0.0260 m

Find

tube diameter (d), in m

Start with the thinking

  • The governing relation printed in this handbook section is Surface tension and capillarity (capillary rise).
  • Everything except d is given, so isolate d 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.
  • A capillary tube experiment illustrates surface tension and capillarity in a small-diameter glass tube.
h = capillary rise

Figure 9 — schematic for Surface tension and capillarity (capillary rise) — solve for tube diameter (case 3) — Surface Tension and Capillarity (9)

Step-by-step solution

  1. Step 1 — State the governing relation:

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}
  2. Step 2 — Rearrange the relation so that d stands alone on the left-hand side.

  3. Step 3 — List the givens: surface tension (sigma) = 0.0730 N/m, wetting angle (theta) = 36.0000 deg, specific weight (gamma) = 9,310 N/m^3, capillary rise (h) = 0.0260 m.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    d=0.0010 md = 0.0010\ \text{m}
  6. Step 6 — Check: returning d = 0.0010 m to

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}

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

Answer:
d=0.0010 md = 0.0010\ \text{m}

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 — Surface Tension and Capillarity

Example 10
Surface tension and capillarity (capillary rise) — solve for capillary rise (case 4) — Surface Tension and Capillarity (10)

surface tension and capillarity in a water-filled capillary tube Given surface tension (sigma) = 0.0790 N/m; wetting angle (theta) = 23.0000 deg; specific weight (gamma) = 9,030 N/m^3; tube diameter (d) = 0.0037 m, determine the capillary rise (h) in m.

Given

  • surfacetension(sigma)=0.0790N/msurface tension (sigma) = 0.0790 N/m
  • wettingangle(theta)=23.0000degwetting angle (theta) = 23.0000 deg
  • specificweight(gamma)=9,030N/m3specific weight (gamma) = 9,030 N/m^3
  • tubediameter(d)=0.0037mtube diameter (d) = 0.0037 m

Find

capillary rise (h), in m

Start with the thinking

  • The governing relation printed in this handbook section is Surface tension and capillarity (capillary rise).
  • Everything except h is given, so isolate h 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.
  • A capillary tube experiment illustrates surface tension and capillarity in a small-diameter glass tube.
h = capillary rise

Figure 10 — schematic for Surface tension and capillarity (capillary rise) — solve for capillary rise (case 4) — Surface Tension and Capillarity (10)

Step-by-step solution

  1. Step 1 — State the governing relation:

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}
  2. Step 2 — Rearrange the relation so that h stands alone on the left-hand side.

  3. Step 3 — List the givens: surface tension (sigma) = 0.0790 N/m, wetting angle (theta) = 23.0000 deg, specific weight (gamma) = 9,030 N/m^3, tube diameter (d) = 0.0037 m.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    h=0.0087 mh = 0.0087\ \text{m}
  6. Step 6 — Check: returning h = 0.0087 m to

    h=4σcos⁡θγdh = \dfrac{4 \sigma \cos\theta}{\gamma d}

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

Answer:
h=0.0087 mh = 0.0087\ \text{m}

Why the other options are there

  • 0.0174 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0044 — dropped that same factor in the other direction.
  • 0.0096 — rounded an intermediate value before the final step.

Reference: FE Handbook — Surface Tension and Capillarity

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