1. Not finding help here? Sign up for a free 30min 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!

Calculating the mass and number of atoms of a structural I beam

  1. Aug 22, 2008 #1
    Please add this title: Calculating the mass and number of atoms of a structural I beam.


    1. The problem statement, all variables and given/known data
    A structural I beam is made of iron> A view of its cross-section and its dimensions is shown in the figure, where d = 2 cm, w= 31 cm, h= 28 cm and the length (not shown) of the beam is L= 1.53 m.
    [​IMG]
    The density of iron is 7560 kg/m^3. The atomic weight of iron is 55.85 g/mol and Avagadro number is Na= 6.02214e23/mol.

    What is the mass of a section 1.53 m long? (in kg)
    How many atoms are there in this section? (in units of atoms)


    3. The attempt at a solution

    I calculated the volume of the I beam ( (h*w*l)-(the volume of the empty space))
    and then I multiply it by the density of iron to get the mass.

    but the answer was wrong, thus i I tried to calculate the number of atoms using Avagadro's number the answer will be wrong as well....

    I hope you help me calculating the mass...

    Thank you
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
    Last edited by a moderator: Aug 22, 2008
  2. jcsd
  3. Aug 22, 2008 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    small earthquake in Chile … not many goldfish

    Hi hsbc2003! :smile:

    hmm … that's a really weird way to do it …

    (and it's very easy to make a mistake that way … always choose a method that's resonably idiot-proof :wink:)

    Hint: the whole cross-section has the same width (2cm),

    so cross-section area A = 2cm x total "length",

    and then volume = A x L. :smile:
     
  4. Aug 22, 2008 #3

    LowlyPion

    User Avatar
    Homework Helper

    Your method looks ok. What numbers did you get? What cross section? Did you keep your units straight?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Calculating the mass and number of atoms of a structural I beam
  1. I-Beam mass (Replies: 3)

Loading...