A solid having the shape of a ball is called a sphere. [Figure 1-28] A sphere has a constant diameter. The radius (r) of a sphere is one-half of the diameter (D). The formula for the volume of a sphere is given as:

V = 4⁄3 × π × radius^{3}= 4⁄3 × π × r

^{3}or V = 1⁄6 × πD

^{3}

Example: A pressure tank inside the fuselage of a cargo aircraft is in the shape of a sphere with a diameter of 34 inches. What is the volume of the pressure tank?

V = 4⁄3 × π × radius

^{3}= 4⁄3 × (3.1416) × (34⁄2)

^{3}= 1.33 × 3.1416 × 17

^{3}= 1.33 × 3.1416 × 4913 V = 20,528.125 cubic inches