Rhode Island Journeyman Plumber Practice Exam

How many feet of 3/4 copper tubing is needed to hold 1 gallon of water?

1. 1

2. 2

3. 3

4. 4

The correct answer is: 2

To determine how many feet of 3/4-inch copper tubing is required to hold 1 gallon of water, it’s essential to understand the volume capacity of the tubing and the spatial characteristics of the cross-section. A 3/4-inch copper tubing has an internal diameter of approximately 0.745 inches. The volume of the water that can be held by a linear foot of this tubing can be calculated using the formula for the volume of a cylinder, which is πr²h, where r is the radius and h is the height (or length in this context). For 3/4-inch copper tubing, the radius is about 0.3725 inches (half of the diameter). Therefore, the cross-sectional area can be calculated as: \[ \text{Area} = π \times (0.3725^2) \approx 0.436 \, \text{square inches} \] To find the volume of 1 foot of the tubing, simply multiply the area by the height (1 foot = 12 inches): \[ \text{Volume per foot} = 0.436 \, \text{square inches} \times 12 \, \text{inches} \approx