1. In a crash simulation, a car traveling at x m/s can stop at a distance d m with a maximum deceleration. If the car is traveling at 2x m/s: A. Stopping time is doubled B. Stopping distance is doubled C. Stopping distance is quadrupled D. Both A and C Ok, so I thought this was a relatively easy question. However, I managed to butcher it. My problem is, I do not understand which equation to use. To find if the distance doubled or quadrupled I used the equation: d = ((Vi + V)/2) * t. Since the car will be stopping the V will be zero and you simply get d = (Vi/2) * t. If the velocity is doubled, distance is doubled. However, the book used the equation V^2 = Vi^2 + 2ad. Thereby getting, stopping distance quadrupled. Also for time they used V = Vi + at. Answer is D. Once again, I am lost to know which equation to use. Since both seemed to work.. Thanks for your help!