1. The problem statement, all variables and given/known data You are asked to design spring bumpers for the walls of a parking garage. A freely rolling 1100 kg car moving at 0.66 m/s is to compress the spring no more than 9.0×10−2m before stopping. What should be the force constant of the spring? Assume that the spring has negligible mass. Express your answer using two significant figures. 2. Relevant equations F=ma w=F*d w=ΛKE 3. The attempt at a solution I Know that the KE o the car is transferred into the PE of the spring .5mv2=.5kx2 Using this method I found the right answer = 59155.5 But this question is in a chapter before PE is mentioned so Id like to see how else it can be solved. I initially tried this method, and would like to know why it is wrong: The car must decelerate during this displacement so using kinematics: 02=662 + 2a(.09) -.4356=2a(.09) a= -2.42 F=ma F=1100*-2.42 F=-2695 so the spring must apply the same force in the opposite direction to stop the cart 29577=k(.09) k= 29577.8 (wrong answer) So why is this method not applicable to this problem? Also should integration be involved here somewhere? Where?