Sphere
Mathematics · FE Reference Handbook section
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.
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
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.
Figure 1 — schematic for Sphere volume and surface area — solve for volume — Sphere
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for V:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
V = 1767\ \text{ft^3}Step 6 — Check: returning V = 1,767 ft^3 to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
Figure 2 — schematic for Sphere volume and surface area — solve for surface area — Sphere (2)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for S:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
S = 36.3168\ \text{ft^2}Step 6 — Check: returning S = 36.3168 ft^2 to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
Figure 3 — schematic for Sphere volume and surface area — solve for radius — Sphere (3)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for r:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning r = 8.5415 ft to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
Figure 4 — schematic for Sphere volume and surface area — solve for volume (case 2) — Sphere (4)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for V:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
V = 623.6\ \text{ft^3}Step 6 — Check: returning V = 623.6 ft^3 to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
Figure 5 — schematic for Sphere volume and surface area — solve for surface area (case 2) — Sphere (5)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for S:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
S = 40.7150\ \text{ft^2}Step 6 — Check: returning S = 40.7150 ft^2 to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
Figure 6 — schematic for Sphere volume and surface area — solve for radius (case 2) — Sphere (6)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for r:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning r = 7.7769 ft to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
Figure 7 — schematic for Sphere volume and surface area — solve for volume (case 3) — Sphere (7)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for V:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
V = 1376\ \text{ft^3}Step 6 — Check: returning V = 1,376 ft^3 to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
Figure 8 — schematic for Sphere volume and surface area — solve for surface area (case 3) — Sphere (8)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for S:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
S = 120.8\ \text{ft^2}Step 6 — Check: returning S = 120.8 ft^2 to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
Figure 9 — schematic for Sphere volume and surface area — solve for radius (case 3) — Sphere (9)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for r:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning r = 9.3894 ft to
reproduces the given quantities, and both sides carry the same units.
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
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
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.
Figure 10 — schematic for Sphere volume and surface area — solve for volume (case 4) — Sphere (10)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for V:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
V = 20.5795\ \text{ft^3}Step 6 — Check: returning V = 20.5795 ft^3 to
reproduces the given quantities, and both sides carry the same units.
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