We have to determine the difference between the stopping distances of the vehicle traveling at 30 mph to the same vehicle traveling at 60 mph. Kinetic energy formula is: KE = 1/2 m v^2. - KE = - (Mi) m g d, where d stays for the stopping distance. Therefore: - 1/2 m v^2 = - (Mi) m g d. ( we can divide both sides by - m ); 1/2 v^2 = (Mi) g d; d = v^2 / 2 (Mi) g . The stopping distance is determined by the square of starting velocity and the effective coefficient of friction between the tires and the road ( Mi ). So d 1 = ( 30 ^2) / 2 (Mi) g = 450/ (mi) g; and: d 2 = ( 60^2 ) / 2 (Mi) g = 1800/ (Mi) g; d 1 : d 2 = 1/4; d 2 = 4 d 1. Answer: It affects that the second stopping distance becomes 4 times greater than the first.