Last updated on July 17th, 2025
The volume of a circle is a concept that extends beyond the usual understanding of a 2D shape to a 3D space. However, in reality, a circle itself is only a 2-dimensional shape, so it does not have volume. Instead, when thinking about volume related to circles, we consider the volume of a sphere, which is a 3D object where all points are equidistant from the center. In this topic, let’s learn about the volume related to circles, specifically focusing on spheres.
To derive the volume of a sphere, we start with the concept of volume as the total space occupied by a 3D object.
The formula for the volume of a sphere is:
Volume = (4/3) × π × r³
This formula:
Uses r, the radius of the sphere.
Includes π to account for the circular symmetry of the sphere.
Incorporates the factor 4/3, which arises from the integration process used in calculus to sum up the infinite thin circular disks that form the sphere.
Although this formula is rooted in integral calculus, it can also be appreciated conceptually as a way to measure how much space is inside a perfectly round 3D shape.
The volume of a sphere is always expressed in cubic units, such as cubic centimeters (cm³) or cubic meters (m³).
To find the volume, follow these steps:
Measure the radius of the sphere.
Use the formula:
Volume = (4/3) × π × r³
Substitute the radius value into the formula and perform the calculations.
This will give you the volume of the sphere in cubic units, representing the 3D space it occupies.
Remember the formula:
The formula for the volume of a sphere is:
Volume = (4/3) × π × r³
Break it down:
The volume is the amount of space inside the sphere.
The radius is the key measurement used to calculate that space.
Simplify the numbers:
If the radius is a simple number like 2, 3, or 4, it's easier to cube it and calculate the volume.
Check for sphere roots:
If you're given the volume and need to find the radius, rearrange the formula and take the cube root to solve backward.
Making mistakes while learning the volume of a sphere is common. Let’s look at some common mistakes and how to avoid them to get a better understanding of the volume of spheres.
A sphere has a radius of 4 cm. What is its volume?
The volume of the sphere is approximately 268.08 cm³.
To find the volume of a sphere, use the formula: V = \( \frac{4}{3} \pi r^3 \) Here, the radius is 4 cm, so: V = \( \frac{4}{3} \pi (4)^3 \approx 268.08 \) cm³
A sphere has a radius of 10 m. Find its volume.
The volume of the sphere is approximately 4188.79 m³.
To find the volume of a sphere, use the formula: V = \( \frac{4}{3} \pi r^3 \) Substitute the radius (10 m): V = \( \frac{4}{3} \pi (10)^3 \approx 4188.79 \) m³
The volume of a sphere is 904.78 cm³. What is the radius of the sphere?
The radius of the sphere is approximately 6 cm.
If you know the volume of the sphere and need to find the radius, take the cube root of the volume divided by 43π\frac{4}{3}\pi34π.
The formula is:
r = ∛( V / ((4/3)π) )
This rearranged version of the volume formula helps you solve for r when V is known.
A sphere has a radius of 2.5 inches. Find its volume.
The volume of the sphere is approximately 65.45 inches³.
Using the formula for volume:
V = (4/3) × π × r³
Step 1: Substitute the radius 2.5 inches:
V = (4/3) × π × (2.5)³
V = (4/3) × π × 15.625
V ≈ (4/3) × 3.1416 × 15.625
V ≈ 65.45 inches³
Therefore, the volume of the sphere is approximately 65.45 cubic inches.
You have a spherical water balloon with a radius of 3 feet. How much space (in cubic feet) does it occupy?
The balloon has a volume of approximately 113.10 cubic feet.
Using the formula for volume:
V = (4/3) × π × r³
Step 1: Substitute the radius 3 feet:
V = (4/3) × π × (3)³
V = (4/3) × π × 27
V ≈ (4/3) × 3.1416 × 27
V ≈ 113.10 ft³
Therefore, the volume of the sphere is approximately 113.10 cubic feet.
Radius: The distance from the center of the sphere to any point on its surface. It is essential for calculating both volume and surface area.
Volume: The amount of space enclosed within a 3D object.
Formula for a sphere:
V=43πr3V = \frac{4}{3} \pi r^3V=34πr3
Sphere: A 3-dimensional shape where all points on the surface are equidistant from the center — like a basketball or a globe.
Cubic Units: Units used to measure volume.
If the radius is in centimeters (cm) → volume is in cubic centimeters (cm³).
If in meters (m) → volume is in cubic meters (m³).
Pi (π): A mathematical constant used in geometry, approximately equal to 3.14159, and common in formulas involving circles and spheres.
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Seyed Ali Fathima S a math expert with nearly 5 years of experience as a math teacher. From an engineer to a math teacher, shows her passion for math and teaching. She is a calculator queen, who loves tables and she turns tables to puzzles and songs.
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