Surface Tension and Capillarity
Fluid Mechanics · FE Reference Handbook section
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.
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
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.
Figure 1 — schematic for Surface tension and capillarity (capillary rise) — solve for capillary rise — Surface Tension and Capillarity
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that h stands alone on the left-hand side.
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.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning h = 0.0034 m to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
Figure 2 — schematic for Surface tension and capillarity (capillary rise) — solve for surface tension — Surface Tension and Capillarity (2)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that sigma stands alone on the left-hand side.
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.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning sigma = 0.0797 N/m to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
Figure 3 — schematic for Surface tension and capillarity (capillary rise) — solve for tube diameter — Surface Tension and Capillarity (3)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that d stands alone on the left-hand side.
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.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning d = 0.0018 m to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that h stands alone on the left-hand side.
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.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning h = 0.0031 m to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that sigma stands alone on the left-hand side.
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.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning sigma = 0.3249 N/m to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that d stands alone on the left-hand side.
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.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning d = 0.0006 m to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that h stands alone on the left-hand side.
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.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning h = 0.0056 m to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that sigma stands alone on the left-hand side.
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.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning sigma = 0.3676 N/m to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that d stands alone on the left-hand side.
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.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning d = 0.0010 m 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 — Surface Tension and Capillarity
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
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.
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that h stands alone on the left-hand side.
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.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning h = 0.0087 m to
reproduces the given quantities, and both sides carry the same units.
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