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## Homework Statement

A structural I-beam is made of steel. L = 12.1 cm, H = 32.0 cm and the width of the beam is W = 1.11 cm. What is the mass of a section 1.75 m long? The density of steel is 7.56E+3 kg/m3.

## Homework Equations

d=m/v

## The Attempt at a Solution

I can't copy the image of the i-beam here.. but, as you might expect, it resembles an i. I found the volume of the total beam, and subtracted from it the volume of the missing section. Then I converted cubic cm to cubic metres and multiplied by the density of steel. Then I found the ratio of length 1.75m to 12.1 cm and multiplied that by my newfound mass.. something is wrong, though.

mass= (7.56e3kg/m^3)((12.1*1.11*32.0-10.99*1.11*29.78)cm^3)(10^-2m/cm)^3/(0.121m)=7.275 kg. Thanks in advance.