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A structural I beam is made of steel. A view of its cross-section and its dimensions are shown in Figure P1.11. The density of steel is 7.56 * 10^3 kg/m^3. What is the mass of the section 8.5 m long?

Figure P1.11 (shown below)

I tried doing this by:

1) changing the 8.5 m into cm... giving me 850 cm.

2) getting the volume by parts: 2[15cm(1cm)(1cm)] + [848cm (1cm)(1cm)]

giving me 878 cm^3.

3) I converted into m^3 and got 8.78*10^-4

4) I used the density and then got a mass of 6.38 kg

But it's a wrong answer... any help would be much appreciated!

Figure P1.11 (shown below)

I tried doing this by:

1) changing the 8.5 m into cm... giving me 850 cm.

2) getting the volume by parts: 2[15cm(1cm)(1cm)] + [848cm (1cm)(1cm)]

giving me 878 cm^3.

3) I converted into m^3 and got 8.78*10^-4

4) I used the density and then got a mass of 6.38 kg

But it's a wrong answer... any help would be much appreciated!

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