# Thread: Volume of a cylinder?

1. ## Volume of a cylinder?

hi all,

just getting stuck on something I know I have answered but forgot how to solve it lol

the question is:

"State the Volume of the metal work." Which is a cylinder pipe.

Outside diameter: 25mm
Wall thickness: 6mm
Length of Pipe: 2m

I know the formula, and how to transpose but I cant seem to get it correct.
the answer is 0.000716m3, according to book, but Im not sure?

2. well you can find the volume by subtracting a cylinder(the hollow part) form a cylinder (the whole pipe fully filled)

the inner diameter of the pipe is d(inner) = (25-12)mm
= 13 mm

the volume of the hollow cylinder = 2*[pi(d(inner))^2]/4
= 0.000265464 m^3

the volume of the fully filled cylinder = 2*[pi(d(outer))^2]/4
= 0.000981747 m^3

therefore the volume of the pipe = 0.000981747 - 0.000265464
= 0.000716283 m^3

3. Hi... how have you got a 12 in there? Did u multiply the thickness by 2?

well you can find the volume by subtracting a cylinder(the hollow part) form a cylinder (the whole pipe fully filled)

the inner diameter of the pipe is d(inner) = (25-12)mm
= 13 mm

the volume of the hollow cylinder = 2*[pi(d(inner))^2]/4
= 0.000265464 m^3

the volume of the fully filled cylinder = 2*[pi(d(outer))^2]/4
= 0.000981747 m^3

therefore the volume of the pipe = 0.000981747 - 0.000265464
= 0.000716283 m^3

4. yup taking the diameter view of the pipe since the pipe has a thickness of 6 mm on both sides hence a multiple of 2

5. Thanks for help,

I remmeber now lol