The finite element method was used to solve the truss problem shown below. The solution for displacements was obtained as \(u_{2}=1.5 \mathrm{~mm}, v_{2}=-1.5 \mathrm{~mm}, u_{3}=3 \mathrm{~mm}\), and \(v_{3}=-1.5\) \(\mathrm{mm}\). Note: the displacements are given in \(\mathrm{mm}\).

a. Determine the axial forces \(P\) in elements 2 and 4 .

b. The forces in elements 3 and 5 are found to be as follows: \(P^{(3)}=-2,000 \mathrm{~N}, P^{(5)}=\) 7,070 N. Determine the support reactions \(R_{y 4}\) at node 4 using the nodal equilibrium equations.

The element properties are listed in the following table.

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Elemi JAE [N] L [m] AT [C] a [1/C] 1 1,2 107 1 -100 10-6 90 2 2,3 107 1 0 106 0 3 3,4 107 1 +100 106-90 4 1,3 107 1.414 +200 10-6 45 5 2,4 107 1.414 +200 10-6-45