a 1250 kg car, rolling at 40km/h along a flat frictionless surface strikes a horizontal coiled spring and is brought to rest in a distance of 2.5m. Assuming there is no friction, what is the spring constant of the spring?
v = 40 km/h =40000/3600 m/s
m•v^2/2 = k•x^2/2
k =m•(v/x)^2