A pipe has a 2-inch diameter and carries water at 3 ft/s. What is the cross-sectional area in square inches and the approximate volumetric flow in ft^3/s?

• A. Area ≈ 1.5708 in^2; Q ≈ 0.0325 ft^3/s.
• B. Area ≈ 2.0944 in^2; Q ≈ 0.098 ft^3/s.
• C. Area ≈ 3.1416 in^2; Q ≈ 0.065 ft^3/s.
• D. Area ≈ 3.0000 in^2; Q ≈ 0.070 ft^3/s.

Answer: (C)

The key idea is that the cross-sectional area of a circular pipe is A = πr^2, and the volumetric flow rate is Q = velocity × area.

With a diameter of 2 inches, the radius is 1 inch, so the area is A = π(1 in)^2 = π square inches ≈ 3.1416 in^2.

To get a flow rate in consistent units, convert the area to square feet: 1 in^2 = 1/144 ft^2, so A ≈ 3.1416 / 144 ≈ 0.02182 ft^2. Multiply by the velocity (3 ft/s): Q ≈ 0.02182 ft^2 × 3 ft/s ≈ 0.0655 ft^3/s.

So the area is about 3.1416 in^2 and the volumetric flow is about 0.065 ft^3/s, which matches the given option.