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

In summary, the conversation discusses the calculation of the mass and number of atoms for a structural I beam made of iron. The dimensions and density of the beam are given, and the method of calculating the mass is discussed. The conversation also mentions attempting to use Avogadro's number to calculate the number of atoms, but encountering incorrect results.
  • #1
hsbc2003
5
0
Please add this title: Calculating the mass and number of atoms of a structural I beam.


Homework Statement


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.
fndyzp.jpg

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)


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
 
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  • #2
small earthquake in Chile … not many goldfish

hsbc2003 said:
I calculated the volume of the I beam ( (h*w*l)-(the volume of the empty space))

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:
 
  • #3
hsbc2003 said:
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,

Your method looks ok. What numbers did you get? What cross section? Did you keep your units straight?
 

1. What is the formula for calculating the mass of a structural I beam?

The formula for calculating the mass of a structural I beam is: mass = density x volume. The density of the material can be found in a materials database, and the volume can be calculated by multiplying the length, width, and height of the beam.

2. How do you determine the number of atoms in a structural I beam?

The number of atoms in a structural I beam can be determined by using Avogadro's number, which is 6.022 x 10^23. This number represents the number of atoms in one mole of a substance. By dividing the mass of the beam by the atomic weight of the material, you can calculate the number of moles and then multiply by Avogadro's number to find the number of atoms.

3. Is the mass and number of atoms the same for every type of structural I beam?

No, the mass and number of atoms will vary depending on the material used to make the structural I beam. Different materials have different densities and atomic weights, which will affect the overall mass and number of atoms in the beam.

4. Can you calculate the mass and number of atoms for a custom-sized structural I beam?

Yes, the mass and number of atoms can be calculated for any size of structural I beam as long as the dimensions and material are known. The same formula and process can be used regardless of the size or shape of the beam.

5. How accurate is the calculation for the mass and number of atoms of a structural I beam?

The accuracy of the calculation will depend on the accuracy of the data used, such as the density and atomic weight of the material. However, with accurate data and precise measurements, the calculated mass and number of atoms should be very close to the actual values.

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