In this finite element problem, the choice of coordinates can influence the formulation of forces and moments but generally does not change the final result if the coordinate system is used consistently across calculations. Here’s a breakdown:

1. Coordinate System: The global coordinate system ($x$-$y$) helps to define the direction of loads and the orientation of elements. In this case, the vertical axis is $y$ and horizontal axis is $x$.

2. Load Distribution: The distributed loads $q_1$ and $q_2$ are applied along the $y$-axis (vertical direction). Since the coordinates are defined properly, each element force vector $f$ and moment $m$ is computed based on this orientation.

3. Moment Calculation: The moment terms ($M_2$) in this problem depend on the distributed loads and the length $L$. By using the formulas given, the moments for each element (like $-12L^2/12$ for $M_1$ and $24L^2/12$ for $M_2$) are computed assuming the loads act vertically along the $y$-axis. So the coordinates are essential for ensuring that moments are calculated in the correct plane.

4. Element Assembly: When the individual elements are assembled, the choice of coordinate orientation allows us to add contributions from each element correctly into the global forces and moments.

In summary, as long as the coordinate system is defined and consistently used across all elements and equations, it does not alter the final result but is crucial for accuracy and consistency.

Would you like further details on any specific part of the calculations?

Related Questions

1. How would the results change if the coordinate system was rotated?
2. What impact does the coordinate system have on moment calculations?
3. How are the distributed loads $q_1$ and $q_2$ derived based on this coordinate system?
4. Could the forces and moments be represented differently with another orientation?
5. How does the finite element model handle internal forces between connected nodes?

Tip

In finite element analysis, always ensure consistent coordinate orientation when assembling global force and moment matrices to avoid errors.