1. 如圖所示，板子承受三個力，試以力扭(Wrench)系統替代此力系系統，試求力扭系統的合力，及力扭作用線通過板子 P 點位置。(25%)

5.如圖三所示(Figure3) Determineθand the tension in the spring, which correspond to the equilibrium position of the spring. The unstretched length of spring is h and the constant of the spring is k. The pin and roller supporters are at A and C, respectively. The point load P works on B with the downward direction and neglect the weight of all objects. (20%)