Find the volume of a sphere by solving for the equation V=4/3*pi*r^3, where V is volume, r stands for radius and pi is 3.1459. Cube the radius, and multiply that number by pi and 4/3 for the volume. Pi delineates the relationship between a circle's diameter and circumference.Continue Reading
Make the equation simpler by inserting 3.1459 for pi and multiplying that figure by 4/3. This creates a value of approximately 4.19453. Now, your equation is V=4.19453*r^3, or the radius cubed times 4.19453.
Replace the variables of the equation with the numbers related to the sphere. For instance, a sphere with a radius of 5 inches means the volume is 4.19453 times 5^3. Five cubed is five times five times five, or 125.
Multiply 125 by 4.19453 to get 524.3167 cubic inches of volume in a sphere with a radius of five inches. You can convert cubic inches to cubic feet by multiplying the volume by 0.000579 to get 0.30358 cubic foot.
Increase or decrease the diameter of a sphere to change the volume. When a sphere changes its diameter by just one inch, the volume changes by 142 cubic inches. If the diameter of this sphere shrinks from 10 inches to 9 inches, the volume is 382.2 cubic inches.