Skip to content

Sphere

Mathematics · FE Reference Handbook section

Mathematics
2 formulas
10 exam-style examples
~49 min
All Mathematics 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
Sphere volume and surface area — solve for volume — Sphere

A tank designer sizes a spherical storage vessel. Given radius (r) = 7.5000 ft; surface area (S) = 676.4 ft^2, determine the volume (V) in ft^3.

Given

  • radius(r)=7.5000ftradius (r) = 7.5000 ft
  • surfacearea(S)=676.4ft2surface area (S) = 676.4 ft^2

Find

volume (V), in ft^3

Start with the thinking

  • The governing relation printed in this handbook section is Sphere volume and surface area.
  • Everything except V is given, so isolate V 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.
  • The sphere volume and surface area formulas relate the radius of a sphere to its volume and area.
r = Sphere geometry

Figure 1 — schematic for Sphere volume and surface area — solve for volume — Sphere

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  2. Step 2 — Rearrange symbolically for V:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  3. Step 3

    Listthegivens:radius(r)=7.5000ft,surfacearea(S)=676.4ft2List the givens: radius (r) = 7.5000 ft, surface area (S) = 676.4 ft^2
  4. Step 4 — Substitute the given values:

    V=43π7.50003V = \dfrac{4}{3}\pi 7.5000^3
  5. Step 5 — Evaluate:

    V = 1767\ \text{ft^3}
  6. Step 6 — Check: returning V = 1,767 ft^3 to

    V=43πr3V = \dfrac{4}{3}\pi r^3

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

Answer:
V = 1767\ \text{ft^3}

Why the other options are there

  • 3,534 — kept a factor of two that cancels in the correct rearrangement.
  • 883.6 — dropped that same factor in the other direction.
  • 1,944 — rounded an intermediate value before the final step.

Reference: FE Handbook — Sphere

Example 2
Sphere volume and surface area — solve for surface area — Sphere (2)

An engineer computes the volume of a spherical dome. Given radius (r) = 1.7000 ft; volume (V) = 2,044 ft^3, determine the surface area (S) in ft^2.

Given

  • radius(r)=1.7000ftradius (r) = 1.7000 ft
  • volume(V)=2,044ft3volume (V) = 2,044 ft^3

Find

surface area (S), in ft^2

Start with the thinking

  • The governing relation printed in this handbook section is Sphere volume and surface area.
  • Everything except S is given, so isolate S 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.
  • The sphere volume and surface area formulas relate the radius of a sphere to its volume and area.
r = Sphere geometry

Figure 2 — schematic for Sphere volume and surface area — solve for surface area — Sphere (2)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  2. Step 2 — Rearrange symbolically for S:

    S=4πr2S = 4\pi r^2
  3. Step 3

    Listthegivens:radius(r)=1.7000ft,volume(V)=2,044ft3List the givens: radius (r) = 1.7000 ft, volume (V) = 2,044 ft^3
  4. Step 4 — Substitute the given values:

    S=4π1.70002S = 4\pi 1.7000^2
  5. Step 5 — Evaluate:

    S = 36.3168\ \text{ft^2}
  6. Step 6 — Check: returning S = 36.3168 ft^2 to

    V=43πr3V = \dfrac{4}{3}\pi r^3

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

Answer:
S = 36.3168\ \text{ft^2}

Why the other options are there

  • 72.6336 — kept a factor of two that cancels in the correct rearrangement.
  • 18.1584 — dropped that same factor in the other direction.
  • 39.9485 — rounded an intermediate value before the final step.

Reference: FE Handbook — Sphere

Example 3
Sphere volume and surface area — solve for radius — Sphere (3)

A student finds the surface area of a sphere given its radius. Given volume (V) = 2,610 ft^3; surface area (S) = 287.1 ft^2, determine the radius (r) in ft.

Given

  • volume(V)=2,610ft3volume (V) = 2,610 ft^3
  • surfacearea(S)=287.1ft2surface area (S) = 287.1 ft^2

Find

radius (r), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Sphere volume and surface area.
  • Everything except r is given, so isolate r 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.
  • The sphere volume and surface area formulas relate the radius of a sphere to its volume and area.
r = Sphere geometry

Figure 3 — schematic for Sphere volume and surface area — solve for radius — Sphere (3)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  2. Step 2 — Rearrange symbolically for r:

    r=3V4π3r = \sqrt[3]{\dfrac{3V}{4\pi}}
  3. Step 3

    Listthegivens:volume(V)=2,610ft3,surfacearea(S)=287.1ft2List the givens: volume (V) = 2,610 ft^3, surface area (S) = 287.1 ft^2
  4. Step 4 — Substitute the given values:

    r=326104π3r = \sqrt[3]{\dfrac{32610}{4\pi}}
  5. Step 5 — Evaluate:

    r=8.5415 ftr = 8.5415\ \text{ft}
  6. Step 6 — Check: returning r = 8.5415 ft to

    V=43πr3V = \dfrac{4}{3}\pi r^3

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

Answer:
r=8.5415 ftr = 8.5415\ \text{ft}

Why the other options are there

  • 17.0830 — kept a factor of two that cancels in the correct rearrangement.
  • 4.2707 — dropped that same factor in the other direction.
  • 9.3956 — rounded an intermediate value before the final step.

Reference: FE Handbook — Sphere

Example 4
Sphere volume and surface area — solve for volume (case 2) — Sphere (4)

A tank designer sizes a spherical storage vessel. Given radius (r) = 5.3000 ft; surface area (S) = 259.1 ft^2, determine the volume (V) in ft^3.

Given

  • radius(r)=5.3000ftradius (r) = 5.3000 ft
  • surfacearea(S)=259.1ft2surface area (S) = 259.1 ft^2

Find

volume (V), in ft^3

Start with the thinking

  • The governing relation printed in this handbook section is Sphere volume and surface area.
  • Everything except V is given, so isolate V 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.
  • The sphere volume and surface area formulas relate the radius of a sphere to its volume and area.
r = Sphere geometry

Figure 4 — schematic for Sphere volume and surface area — solve for volume (case 2) — Sphere (4)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  2. Step 2 — Rearrange symbolically for V:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  3. Step 3

    Listthegivens:radius(r)=5.3000ft,surfacearea(S)=259.1ft2List the givens: radius (r) = 5.3000 ft, surface area (S) = 259.1 ft^2
  4. Step 4 — Substitute the given values:

    V=43π5.30003V = \dfrac{4}{3}\pi 5.3000^3
  5. Step 5 — Evaluate:

    V = 623.6\ \text{ft^3}
  6. Step 6 — Check: returning V = 623.6 ft^3 to

    V=43πr3V = \dfrac{4}{3}\pi r^3

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

Answer:
V = 623.6\ \text{ft^3}

Why the other options are there

  • 1,247 — kept a factor of two that cancels in the correct rearrangement.
  • 311.8 — dropped that same factor in the other direction.
  • 686.0 — rounded an intermediate value before the final step.

Reference: FE Handbook — Sphere

Example 5
Sphere volume and surface area — solve for surface area (case 2) — Sphere (5)

An engineer computes the volume of a spherical dome. Given radius (r) = 1.8000 ft; volume (V) = 3,631 ft^3, determine the surface area (S) in ft^2.

Given

  • radius(r)=1.8000ftradius (r) = 1.8000 ft
  • volume(V)=3,631ft3volume (V) = 3,631 ft^3

Find

surface area (S), in ft^2

Start with the thinking

  • The governing relation printed in this handbook section is Sphere volume and surface area.
  • Everything except S is given, so isolate S 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.
  • The sphere volume and surface area formulas relate the radius of a sphere to its volume and area.
r = Sphere geometry

Figure 5 — schematic for Sphere volume and surface area — solve for surface area (case 2) — Sphere (5)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  2. Step 2 — Rearrange symbolically for S:

    S=4πr2S = 4\pi r^2
  3. Step 3

    Listthegivens:radius(r)=1.8000ft,volume(V)=3,631ft3List the givens: radius (r) = 1.8000 ft, volume (V) = 3,631 ft^3
  4. Step 4 — Substitute the given values:

    S=4π1.80002S = 4\pi 1.8000^2
  5. Step 5 — Evaluate:

    S = 40.7150\ \text{ft^2}
  6. Step 6 — Check: returning S = 40.7150 ft^2 to

    V=43πr3V = \dfrac{4}{3}\pi r^3

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

Answer:
S = 40.7150\ \text{ft^2}

Why the other options are there

  • 81.4301 — kept a factor of two that cancels in the correct rearrangement.
  • 20.3575 — dropped that same factor in the other direction.
  • 44.7865 — rounded an intermediate value before the final step.

Reference: FE Handbook — Sphere

Example 6
Sphere volume and surface area — solve for radius (case 2) — Sphere (6)

A student finds the surface area of a sphere given its radius. Given volume (V) = 1,970 ft^3; surface area (S) = 745.5 ft^2, determine the radius (r) in ft.

Given

  • volume(V)=1,970ft3volume (V) = 1,970 ft^3
  • surfacearea(S)=745.5ft2surface area (S) = 745.5 ft^2

Find

radius (r), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Sphere volume and surface area.
  • Everything except r is given, so isolate r 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.
  • The sphere volume and surface area formulas relate the radius of a sphere to its volume and area.
r = Sphere geometry

Figure 6 — schematic for Sphere volume and surface area — solve for radius (case 2) — Sphere (6)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  2. Step 2 — Rearrange symbolically for r:

    r=3V4π3r = \sqrt[3]{\dfrac{3V}{4\pi}}
  3. Step 3

    Listthegivens:volume(V)=1,970ft3,surfacearea(S)=745.5ft2List the givens: volume (V) = 1,970 ft^3, surface area (S) = 745.5 ft^2
  4. Step 4 — Substitute the given values:

    r=319704π3r = \sqrt[3]{\dfrac{31970}{4\pi}}
  5. Step 5 — Evaluate:

    r=7.7769 ftr = 7.7769\ \text{ft}
  6. Step 6 — Check: returning r = 7.7769 ft to

    V=43πr3V = \dfrac{4}{3}\pi r^3

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

Answer:
r=7.7769 ftr = 7.7769\ \text{ft}

Why the other options are there

  • 15.5538 — kept a factor of two that cancels in the correct rearrangement.
  • 3.8885 — dropped that same factor in the other direction.
  • 8.5546 — rounded an intermediate value before the final step.

Reference: FE Handbook — Sphere

Example 7
Sphere volume and surface area — solve for volume (case 3) — Sphere (7)

A tank designer sizes a spherical storage vessel. Given radius (r) = 6.9000 ft; surface area (S) = 712.0 ft^2, determine the volume (V) in ft^3.

Given

  • radius(r)=6.9000ftradius (r) = 6.9000 ft
  • surfacearea(S)=712.0ft2surface area (S) = 712.0 ft^2

Find

volume (V), in ft^3

Start with the thinking

  • The governing relation printed in this handbook section is Sphere volume and surface area.
  • Everything except V is given, so isolate V 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.
  • The sphere volume and surface area formulas relate the radius of a sphere to its volume and area.
r = Sphere geometry

Figure 7 — schematic for Sphere volume and surface area — solve for volume (case 3) — Sphere (7)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  2. Step 2 — Rearrange symbolically for V:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  3. Step 3

    Listthegivens:radius(r)=6.9000ft,surfacearea(S)=712.0ft2List the givens: radius (r) = 6.9000 ft, surface area (S) = 712.0 ft^2
  4. Step 4 — Substitute the given values:

    V=43π6.90003V = \dfrac{4}{3}\pi 6.9000^3
  5. Step 5 — Evaluate:

    V = 1376\ \text{ft^3}
  6. Step 6 — Check: returning V = 1,376 ft^3 to

    V=43πr3V = \dfrac{4}{3}\pi r^3

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

Answer:
V = 1376\ \text{ft^3}

Why the other options are there

  • 2,752 — kept a factor of two that cancels in the correct rearrangement.
  • 688.0 — dropped that same factor in the other direction.
  • 1,514 — rounded an intermediate value before the final step.

Reference: FE Handbook — Sphere

Example 8
Sphere volume and surface area — solve for surface area (case 3) — Sphere (8)

An engineer computes the volume of a spherical dome. Given radius (r) = 3.1000 ft; volume (V) = 1,367 ft^3, determine the surface area (S) in ft^2.

Given

  • radius(r)=3.1000ftradius (r) = 3.1000 ft
  • volume(V)=1,367ft3volume (V) = 1,367 ft^3

Find

surface area (S), in ft^2

Start with the thinking

  • The governing relation printed in this handbook section is Sphere volume and surface area.
  • Everything except S is given, so isolate S 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.
  • The sphere volume and surface area formulas relate the radius of a sphere to its volume and area.
r = Sphere geometry

Figure 8 — schematic for Sphere volume and surface area — solve for surface area (case 3) — Sphere (8)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  2. Step 2 — Rearrange symbolically for S:

    S=4πr2S = 4\pi r^2
  3. Step 3

    Listthegivens:radius(r)=3.1000ft,volume(V)=1,367ft3List the givens: radius (r) = 3.1000 ft, volume (V) = 1,367 ft^3
  4. Step 4 — Substitute the given values:

    S=4π3.10002S = 4\pi 3.1000^2
  5. Step 5 — Evaluate:

    S = 120.8\ \text{ft^2}
  6. Step 6 — Check: returning S = 120.8 ft^2 to

    V=43πr3V = \dfrac{4}{3}\pi r^3

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

Answer:
S = 120.8\ \text{ft^2}

Why the other options are there

  • 241.5 — kept a factor of two that cancels in the correct rearrangement.
  • 60.3814 — dropped that same factor in the other direction.
  • 132.8 — rounded an intermediate value before the final step.

Reference: FE Handbook — Sphere

Example 9
Sphere volume and surface area — solve for radius (case 3) — Sphere (9)

A student finds the surface area of a sphere given its radius. Given volume (V) = 3,467 ft^3; surface area (S) = 497.7 ft^2, determine the radius (r) in ft.

Given

  • volume(V)=3,467ft3volume (V) = 3,467 ft^3
  • surfacearea(S)=497.7ft2surface area (S) = 497.7 ft^2

Find

radius (r), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Sphere volume and surface area.
  • Everything except r is given, so isolate r 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.
  • The sphere volume and surface area formulas relate the radius of a sphere to its volume and area.
r = Sphere geometry

Figure 9 — schematic for Sphere volume and surface area — solve for radius (case 3) — Sphere (9)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  2. Step 2 — Rearrange symbolically for r:

    r=3V4π3r = \sqrt[3]{\dfrac{3V}{4\pi}}
  3. Step 3

    Listthegivens:volume(V)=3,467ft3,surfacearea(S)=497.7ft2List the givens: volume (V) = 3,467 ft^3, surface area (S) = 497.7 ft^2
  4. Step 4 — Substitute the given values:

    r=334674π3r = \sqrt[3]{\dfrac{33467}{4\pi}}
  5. Step 5 — Evaluate:

    r=9.3894 ftr = 9.3894\ \text{ft}
  6. Step 6 — Check: returning r = 9.3894 ft to

    V=43πr3V = \dfrac{4}{3}\pi r^3

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

Answer:
r=9.3894 ftr = 9.3894\ \text{ft}

Why the other options are there

  • 18.7788 — kept a factor of two that cancels in the correct rearrangement.
  • 4.6947 — dropped that same factor in the other direction.
  • 10.3284 — rounded an intermediate value before the final step.

Reference: FE Handbook — Sphere

Example 10
Sphere volume and surface area — solve for volume (case 4) — Sphere (10)

A tank designer sizes a spherical storage vessel. Given radius (r) = 1.7000 ft; surface area (S) = 439.6 ft^2, determine the volume (V) in ft^3.

Given

  • radius(r)=1.7000ftradius (r) = 1.7000 ft
  • surfacearea(S)=439.6ft2surface area (S) = 439.6 ft^2

Find

volume (V), in ft^3

Start with the thinking

  • The governing relation printed in this handbook section is Sphere volume and surface area.
  • Everything except V is given, so isolate V 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.
  • The sphere volume and surface area formulas relate the radius of a sphere to its volume and area.
r = Sphere geometry

Figure 10 — schematic for Sphere volume and surface area — solve for volume (case 4) — Sphere (10)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  2. Step 2 — Rearrange symbolically for V:

    V=43πr3V = \dfrac{4}{3}\pi r^3
  3. Step 3

    Listthegivens:radius(r)=1.7000ft,surfacearea(S)=439.6ft2List the givens: radius (r) = 1.7000 ft, surface area (S) = 439.6 ft^2
  4. Step 4 — Substitute the given values:

    V=43π1.70003V = \dfrac{4}{3}\pi 1.7000^3
  5. Step 5 — Evaluate:

    V = 20.5795\ \text{ft^3}
  6. Step 6 — Check: returning V = 20.5795 ft^3 to

    V=43πr3V = \dfrac{4}{3}\pi r^3

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

Answer:
V = 20.5795\ \text{ft^3}

Why the other options are there

  • 41.1591 — kept a factor of two that cancels in the correct rearrangement.
  • 10.2898 — dropped that same factor in the other direction.
  • 22.6375 — rounded an intermediate value before the final step.

Reference: FE Handbook — Sphere

© 2026 Dr. Steve Efe. Civil Engineering Capstone Studio. All rights reserved.