Sphere Calculator

Uses Pi = 3.14159265359 for precise calculations.


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What is a Sphere?

A sphere is a perfectly round three-dimensional object where every point on its surface is equidistant from its center. Common examples include balls, globes, and planets.

Sphere Formulas

Volume Formula

The volume of a sphere is calculated as:

V = (4/3) * Pi * r^3

Surface Area Formula

The surface area of a sphere is:

A = 4 * Pi * r^2

Diameter Formula

d = 2r

Reverse Formulas

From Volume:   r = cuberoot(3V / (4 * Pi))
From Surface Area:   r = sqrt(A / (4 * Pi))

Understanding the Formulas

Why (4/3)Pi*r^3?

The volume formula comes from calculus - integrating circular cross-sections. The (4/3) factor appears because a sphere can be thought of as composed of infinitely many infinitesimally thin circular disks stacked together.

Why 4Pi*r^2?

The surface area is exactly 4 times the area of a circle with the same radius. This is because a sphere can be "unwrapped" to cover exactly 4 circles of radius r.

Example Calculations

Example 1: From Radius

Given radius = 5 units:

Volume = (4/3) * Pi * 5^3
      = (4/3) * Pi * 125
      = 166.67 * Pi
      = 523.6 cubic units

Surface Area = 4 * Pi * 5^2
            = 4 * Pi * 25
            = 100 * Pi
            = 314.16 square units

Example 2: From Diameter

Given diameter = 10 units:

Radius = 10 / 2 = 5 units
Volume = (4/3) * Pi * 5^3 = 523.6 cubic units
Surface Area = 4 * Pi * 5^2 = 314.16 square units

Example 3: From Volume

Given volume = 100 cubic units:

r = cuberoot(3 * 100 / (4 * Pi))
r = cuberoot(300 / 12.566)
r = cuberoot(23.87)
r = 2.88 units

Applications

Science

Calculating volumes of atoms, cells, planets, and stars.

Engineering

Designing spherical tanks, ball bearings, and pressure vessels.

Sports

Manufacturing balls for various sports (basketball, soccer, tennis, golf).

Daily Life

Determining how much paint for a spherical object, or water volume in a spherical tank.

Related Shapes

  • Circle: A 2D cross-section of a sphere
  • Hemisphere: Half of a sphere
  • Ellipsoid: A "stretched" sphere

Interesting Facts

  • A sphere has the smallest surface area for a given volume
  • Soap bubbles form spheres because surface tension minimizes surface area
  • The Earth is not a perfect sphere - it's slightly flattened at the poles
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