For the following mechanical system, assume the two masses (m, and m.) are in horizontal plane, therefore no gravity needed to be considered. An external forces F is applied on mass m. The length of the rod is L. The ma of the spring K, is L. You are required: 1) Assume the rod is massless and rigid, plot the bond graph model and assign causality bars and identify state variables (5 points); Part 2) and 3) are in the next page!!! K -bz SF X 2) Assume the rod can be treated as an equivalent spring (K), the length of the link now is a variable r, please plot the bond graph of the system (8 points), assign causal bars (2 points), and Derive state equations (14 points). 3) Write the output functions for velocity of m, spring force for K., and damping force for b respectively (6 points).