[填空题]
A 950-kg car strikes a huge spr rhu5td9ip2.z53vzt iing at a spz+t kon7-py05ou + kngeed of 22 m/s (Fig. 11–54), compressing the spring 5.0 m. u -yn5o7k+t pn+0z okg(a) What is the spring stiffness constant of the spring? N/m (b) How long is the car in contact with the spring before it bounces off in the opposite direction? s