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Tuesday, April 23, 2013

Right Circular Cylinder - Sphere

Category: Solid Geometry

"Published in Newark, California, USA"

Two balls, one 6 in. in diameter and the other 4 in. in diameter are placed in a cylindrical jar 9 in. in diameter, as shown. Find the volume of water necessary to cover them.


Photo by Math Principles in Everyday Life

Solution:

The first that we have to do is to analyze and label the given figure as follows


Photo by Math Principles in Everyday Life

Consider a right triangle between the centers of two spheres and use Pythagorean Theorem in order to solve for x as follows













The height of a right circular cylinder is







The volume of a right circular cylinder is









The volume of a big sphere is









The volume of a small sphere is







Therefore, the volume of water necessary to cover the two balls is











or you can give the value of pi as follows