1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Volume of a cylinder

  1. Nov 1, 2013 #1
    1. The problem statement, all variables and given/known data

    a hollow cylindrical copper pipe is 1.5m long and has an outside diameter of 35cm and an inside diameter of 2.5 cm how much does it weight?

    2. Relevant equations

    ρ = M/V = 8.9E3
    w = Mg

    3. The attempt at a solution

    okay, so I know that I can just solve for M because I already have ρ but how do I find volume? do I just do πr^2h but what do I do with the inner and outer diameters?
  2. jcsd
  3. Nov 1, 2013 #2


    Staff: Mentor

    Are you sure about the dimensions of your cylinder? As you gave them, you have a nearly solid chunk of copper with a narrow hole in the middle.

    The "hole" is also a cylinder, so you can find its volume and subtract that from the larger volume.
  4. Nov 4, 2013 #3
    Assuming that OP meant 3.5cm, and 2.5cm respectively;

    Use your equation for the Volume of Cylinder:
    [tex]V = \pi r^2 h[/tex]
    So like Mark said - find the volume of the cylinder and subtract the volume of the inner 'cylinder' and then you will have the V to find your weight with. (converting cm to m):

    [tex]V_{outer} = \pi (0.035m)^2 (1.5m)[/tex]
    [tex] V_{inner} = \pi (0.025m)^2 (1.5m)[/tex]
    [tex] V_{outer} - V_{inner} = V_{pipe}[/tex]

    (in cubic meters)

    Now you can find the Mass.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted