Cones, Cylinders, & Spheres Unit Test

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Question
The volume of a sphere is 48 m3
. What is the volume of a cylinder if its radius is the same as the sphere’s and its height is equal to the sphere’s diameter?(1 point)
m3
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1 answer

To find the volume of the cylinder, we first need to find the radius of the sphere from its volume. The volume \( V \) of a sphere is given by the formula:

\[ V = \frac{4}{3} \pi r^3 \]

Given that the volume of the sphere is \( 48 , m^3 \), we can set up the equation:

\[ \frac{4}{3} \pi r^3 = 48 \]

To solve for \( r \), we first rearrange the equation:

\[ r^3 = \frac{48 \times 3}{4\pi} \]

Calculating this gives:

\[ r^3 = \frac{144}{4\pi} = \frac{36}{\pi} \]

Now we can take the cube root to find \( r \):

\[ r = \sqrt[3]{\frac{36}{\pi}} \]

Next, we will calculate the diameter \( d \) of the sphere:

\[ d = 2r = 2 \times \sqrt[3]{\frac{36}{\pi}} \]

Now that we have both the radius \( r \) for the cylinder and its height \( h \) (equal to the diameter of the sphere), we can write the volume formula for the cylinder. The volume \( V \) of a cylinder is given by:

\[ V = \pi r^2 h \]

We substitute \( h \) with \( 2r \):

\[ V = \pi r^2 (2r) = 2\pi r^3 \]

We know from earlier that \( \frac{4}{3} \pi r^3 = 48 \). Thus, we can find \( r^3 \):

\[ r^3 = \frac{48 \times 3}{4\pi} = \frac{144}{4\pi} = \frac{36}{\pi} \]

Now substituting \( r^3 \) into the volume formula for the cylinder:

\[ V = 2\pi \left(\frac{36}{\pi}\right) = 2 \times 36 = 72 , m^3 \]

Therefore, the volume of the cylinder is:

\[ \boxed{72} , m^3 \]