McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
6. Surface Areas and Volumes of Spheres
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Exercise 38 Page 853

Convert all units to the same measurement.

The volume of the sphere is greater than the volume of the cylinder.

Practice makes perfect

We are asked to find which has greater volume: a sphere with a radius of r=2.3 yards or a cylinder with a radius of r= 4 feet and height of h= 8 feet. First, let's find the radius of the sphere in terms of feet. Since 1 yard is 3 feet, the radius of the sphere is r=3* 2.3= 6.9 feet.

From the above diagram, we can say that the volume of the sphere is bigger. But, we should check it by finding the volumes. To find the volumes of the cylinder and the sphere, we will use the formulas for the volume of a cylinder, and for the volume of a sphere.

Solid Cylinder Sphere
Radius r= 4 r= 6.9
Height h= 8 -
Volume V_\text{cylinder}=\pi {\color{#0000FF}{r}}^2{\color{#009600}{h}} V_\text{sphere}=\dfrac{4}{3}\pi {\color{#0000FF}{r}}^3
\textcolor{darkorange}{V_\text{cylinder}}=\pi({\color{#0000FF}{4}})^2({\color{#009600}{8}})=\textcolor{darkorange}{128\pi} \textcolor{darkviolet}{V_\text{sphere}}=\dfrac{4}{3}\pi({\color{#0000FF}{6.9}})^3=\textcolor{darkviolet}{438.012\pi}

The volume of the sphere, which is \textcolor{darkviolet}{V_\text{sphere}}=\textcolor{darkviolet}{438.012\pi} cubic feet, is greater than the volume of the cylinder, \textcolor{darkorange}{V_\text{cylinder}}=\textcolor{darkorange}{128\pi}.