1. The problem statement, all variables and given/known data What should be the spring constant k of a spring designed to bring a 1260 kg car to rest from a speed of 88 km/h so that the occupants undergo a maximum acceleration of 5.0 g? 2. Relevant equations F=ma v2=v02 + 2a(x-x0 F=-kx 3. The attempt at a solution First I converted 88km/h to 24.4 m/s Then I found the F, by using F=ma F= (1260) * (49) <--changed acceleration from g to m/s2 So I got 61740 for F Then I decided to find x I used the velocity equation 0 = (24.4)2 + 2 * -49x Solving for x gave me 6.08 Then I plugged that into the F=-kx equation and I got k = 10155 But this is wrong!! I even tried putting in -10155 What am I doing wrong? I don't understand.