A collar of Styrofoam is made to insulate a pipe. Find its volume. The large radius R is to the outer rim. The small radius r is to the edge of the insulation. Use pi almost equals 3.14 .

r
​=
2 in.
R
​=
4 in.
h
​=
16 in.
Question content area bottom
Part 1
The volume of the Styrofoam collar is approximately
  
enter your response here in. cubed
​(Round to two decimal​ places.)

1 answer

To find the volume of the Styrofoam collar, we can calculate the volume of the larger cylinder (with radius \( R \)) and subtract the volume of the smaller cylinder (with radius \( r \)). The formula for the volume \( V \) of a cylinder is given by:

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

where \( r \) is the radius and \( h \) is the height (or length) of the cylinder.

  1. Volume of the larger cylinder (radius \( R \)):

    \[ V_{\text{large}} = \pi R^2 h = \pi (4 \text{ in.})^2 (16 \text{ in.}) \]

    Calculating this:

    \[ = \pi \cdot 16 \cdot 16 = 256 \pi \]

    Now, using \( \pi \approx 3.14 \):

    \[ V_{\text{large}} \approx 256 \cdot 3.14 = 804.64 \text{ in.}^3 \]

  2. Volume of the smaller cylinder (radius \( r \)):

    \[ V_{\text{small}} = \pi r^2 h = \pi (2 \text{ in.})^2 (16 \text{ in.}) \]

    Calculating this:

    \[ = \pi \cdot 4 \cdot 16 = 64 \pi \]

    Again using \( \pi \approx 3.14 \):

    \[ V_{\text{small}} \approx 64 \cdot 3.14 = 200.96 \text{ in.}^3 \]

  3. Volume of the Styrofoam collar:

    \[ V_{\text{collar}} = V_{\text{large}} - V_{\text{small}} = 804.64 \text{ in.}^3 - 200.96 \text{ in.}^3 \]

    \[ V_{\text{collar}} \approx 603.68 \text{ in.}^3 \]

Finally, rounding to two decimal places, the volume of the Styrofoam collar is:

\[ \boxed{603.68} \text{ in.}^3 \]