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Question

A PVC pipe has a diameter of 5 inches. The whole in the pipe has a diameter of 4.8 inches. If the pipe is 6 ft long, what is its volume? Round to the nearest tenth.

Answer 1

A pipe forms a cylinder that is 6 feet long for this example. Do not forget to convert all units to inches or all units to feet when doing this problem. I have converted all units to inches. To find the volume of the pipe you need to take the outside radius to come up with the total volume of the 6 ft. long pipe and then subtract the inside volume of the open space of the pipe. Both the outside and inside of the pipe forms cylinders. Total volume of the outside of the pipe and the inside space is found by taking the area of the base which is a circle (π•r²) and multiplying it by the height of 72 inches. The outside radius r₁ is 2.5 inches (diameter of 5 inches). You then subtract the inside volume of the open space by using (π•r²) times the height (72 inches). The inside radius r₂ of the open space is 2.4 inches (diameter of 4.8 inches). Remember that the height is the length of the pipe which is 6 feet long or 72 inches. The answer is rounded to the nearest tenth.

Volume = π • r₁² • h - π • r₂² • h

Volume = π • (2.5)² • 72 - π •(2.4)² • 72

Volume = 110.8 in³

Answer 2

Volume = (area of base) x (height)

Since a pipe is a cylinder, with a circular base, you will calculate the area of the circle and multiply it by the height/length of the pipe.

Area of circle = π*r²

Radius (r) is half the diameter.

So V = π*r²*h

You just need to plug in the values given in the problem.

Answer 3

Volume of cylinder = πr²h, where r = radius and h = height.

Volume of pipe = π(2.5)²(6) - π(2.4)²(6)