Exercise $1$: For the spring assemblages shown to the right, $($a$)$ assemble the global stiffness matrix, $($b$)$ determine the nodal displacements and $($c$)$ the reaction forces $($text problem P$2-17,$ note the change in node numbering$).$ Let the spring constants $k_1=500\frac{N}{mm},k_2=k_3=300\frac{N}{mm},$ and $k_4=k_5=400\frac{N}{m}m.$