(a) The spring stiffness constant of the spring is 18,392 N/m.
(b) The time the car was in contact with the spring before it bounces off in the opposite direction is 0.23 s.
The kinetic energy of the car is calculated as follows;
K.E = ¹/₂mv²
K.E = ¹/₂ x 950 x 22²
K.E = 229,900 J
The stiffness constant of the spring is calculated as follows;
K.E =  U = ¹/₂kx²
k = 2U/x²
k = (2 x 229,900)/(5)²
k = 18,392 N/m
F = kx
F = 18,392 x 5
F = 91,960 N
F = mv/t
t = mv/F
t = (950 x 22)/(91960)
t = 0.23 s
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