申論題

5.As shown in Figure 5, a 1-kg block A is pushed up against a spring compressing it a distance x. The block is then released from rest and slides down the 20° incline until it strikes a 1-kg sphere B which is suspended from a 1-m inextensible rope. The spring constant k =800 N/m, the coefficient of friction between A and the ground is 0.2, the distance A slides from the unstretched length of the spring d =1.5 m and the coeficient of restitution between A and B is 0.8. Knowing the tension in the rope is 20 N when a = 20° , determine initial compression x of the spring. (20%)