Problem 4. (a) Determine the equivalent stiffness for the figure below as a single spring system. k. F k k3 Figure. Multiple springs in series and parallel (b) Analyze forces/moments on the systems using free body diagrams and write the dynamic equations (equations of motion). k m d We assume followings. - No gravity - At x = 0, the spring force is 0. - At x = 0, the damping force is 0.