In: Physics
Given is:-
Mass of the car 
speed of the car 
compression in the spring 
At the instant of maximum compression the speed of the car reduces to zero. Taking the kinetic energy of the car to be zero at the horizontal part, the conservation of energy shows

or

by putting all the values


Thus the stiffness of the spring or the spring constant is 3792.6N/m
Part-b
we know that
the time period of the osillation of spring is

where m is the mass of the particle and k is the spring constant
And time for maximum compression is = 
Thus time taken for maximum compression is t

by putting all the values we get

Therefore the Darth Maul's car takes 0.74 seconds before it bounces off in the opposite direction