Refer to Figure 107.1401. The contract requires the electrical contractor to set steel posts (bollards) around a pad-mounted transformer. You are going to use 10-foot-long pieces of 6" (inside diameter) pipe for the posts. You will need sixteen (16) of these posts and you are going to have to fill each of these with concrete.


To determine the amount of concrete required to fill the sixteen 10-foot-long bollards, we need to calculate the volume of each steel post and then multiply by 16. 

Here’s the approach:

### Step 1: Volume of a cylinder (post)
Each bollard is a cylinder. The formula for the volume of a cylinder is:

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

where:
- \( V \) is the volume,
- \( r \) is the radius (half the inside diameter of the pipe),
- \( h \) is the height of the cylinder,
- \( \pi \) is approximately 3.1416.

### Step 2: Calculate the radius
Since the inside diameter of the pipe is given as 6 inches, we can calculate the radius:

\[
r = \frac{6}{2} = 3 \text{ inches}
\]

Convert inches to feet since the height is given in feet:

\[
r = \frac{3}{12} = 0.25 \text{ feet}
\]

### Step 3: Height of the post
The height of the post is 10 feet (as given in the problem).

### Step 4: Calculate the volume for one bollard
Now, use the formula for the volume of a cylinder:

\[
V = \pi (0.25)^2 (10)
\]
\[
V = 3.1416 \times 0.0625 \times 10
\]
\[
V = 1.9635 \text{ cubic feet}
\]

### Step 5: Calculate the total volume for 16 bollards
Since you need 16 posts, the total volume of concrete required will be:

\[
\text{Total Volume} = 16 \times 1.9635 = 31.416 \text{ cubic feet}
\]

Thus, you will need approximately **31.42 cubic feet** of concrete to fill all 16 bollards.

---

Do you want more details on this calculation or have any questions?

### Relative Questions:
1. How do you convert cubic feet to cubic yards for concrete?
2. If the outside diameter of the pipe is 8 inches, how would you calculate the amount of concrete required if you also filled the space between the pipe and the post hole?
3. What would be the weight of the concrete used if the density of concrete is 150 lb/ft³?
4. How would the volume change if the height of the posts was reduced to 8 feet?
5. If you decided to reinforce the bollards with rebar, how would this affect the volume of concrete required?

### Tip:
Always double-check the inside diameter of the pipe, as the volume calculation assumes that no additional space between the outer surface of the bollard and the ground will be filled with concrete.

Refer to Figure 107.1401. The contract requires the electrical contractor to set steel posts (bollards) around a pad-mounted transformer. You are going to use 10-foot-long pieces of 6" (inside diameter) pipe for the posts. You will need sixteen (16) of these posts and you are going to have to fill each of these with concrete.

Learn how to calculate the total concrete required to fill 16 steel bollards, each 10 feet long with a 6-inch inside diameter, using the volume of a cylinder formula. This problem involves geometry concepts and unit conversion. Suitable for high school students in Grades 10-12.

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