Engineering Which is the strongest of these 3 beam cross sections?

Kalle
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Homework Statement
The 3 metre long butcher block is loaded to 30KN/m.There are three cross-section options.
1. 45x 220 rectangular cross section (vertical).
2. T-shaped cross-section formed by two 45 x 220 cross-sections.
3. I-shaped cross-section formed by three 45 x 220 cross-sections.
Find the internal forces and draw the internal force curves.Check which of the three cross sections is the most suitable(meets the requirements with minimum material consumption).Submit the calculations for all variants(fm 16N/mm2)For the most suitable variant, draw the normal stress epoxy and the shear stress epoxy principle shape. I solved points 1 and 2. Please check if it is correct.
I attach the solution steps.
Relevant Equations
V = ql/2; M=ql2/8
Added solutions. Check if there is a correct solution.

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Thread 'Why wasn’t gravity included in the potential energy for this problem?'
I’m looking at the attached vibration problem. The solution in the manual includes the spring potential energy but does NOT include the gravitational potential energy of the hanging mass. Can someone explain why gravitational potential energy is not included when deriving the equation of motion? I tried asking ChatGPT but kept going in circles and couldn't figure out. Thanks!

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