1. The problem statement, all variables and given/known data A 1200 kg car rolling on a horizontal surface has speed v=65km/h when it strikes a horizontal coiled spring and is brought to rest in a distance of 2.2m. what is the spring stiffness constant of the spring? 2. Relevant equations K(final)+Us(final)=K(initial)+Us(initial) 1/2mv^2 + 1/2k(delta x)^2= 1/2mv^2 + 1/2k(delta x)^2 3. The attempt at a solution 1/2(1200)(0) + 1/2k(2.2)^2 = 1/2(1200)(18.06) + 1/2k(0)^2 k = 80867.00826 N/m The answer looks so big that it doesnt make sense to me. I converted the 65km/h to m/s. thanks, nicole!