A 950-kg car strikes a huge spring at a speed of 22m/s (Fig. 11-54), compressing the spring

Question:

A 950-kg car strikes a huge spring at a speed of 22m/s (Fig. 11-54), compressing the spring 5.0 m.
(a) What is the spring stiffness constant of the spring?
(b) How long is the car in contact with the spring before it bounces off in the opposite direction?

900 kg