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=> The volume of a sphere is 2/3 of the volume of a cylinder with same radius, and height equal to the diameter. NOTE: The formula for the volume of a sphere is 4⁄3πr³. For a cylinder, the formula is πr²h. A cone is ⅓ the volume of a cylinder, or 1⁄3πr²h. #CarryOnLearning
Volume of a Cone vs CylinderLet's fit a cylinder around a cone. The volume formulas for cones and cylinders are very similar:
So the cone's volume is exactly one third ( 1 3 ) of a cylinder's volume. (Try to imagine 3 cones fitting inside a cylinder, if you can!) Volume of a Sphere vs CylinderNow let's fit a cylinder around a sphere . We must now make the cylinder's height 2r so the sphere fits perfectly inside.
So the sphere's volume is 4 3 vs 2 for the cylinder Or more simply the sphere's volume is 2 3 of the cylinder's volume! The ResultAnd so we get this amazing thing that the volume of a cone and sphere together make a cylinder (assuming they fit each other perfectly, so h=2r): Isn't mathematics wonderful? Question: what is the relationship between the volume of a cone and half a sphere (a hemisphere)? Surface AreaWhat about their surface areas? No, it does not work for the cone. But we do get the same relationship for the sphere and cylinder (2 3 vs 1) And there is another interesting thing: if we remove the two ends of the cylinder then its surface area is exactly the same as the sphere: Which means that we could reshape a cylinder (of height 2r and without its ends) to fit perfectly on a sphere (of radius r): Same Area (Research "Archimedes' Hat-Box Theorem" to learn more.) Copyright © 2018 MathsIsFun.com |