2. How does kinetic energy affect the stopping distance of a vehicle traveling at 30 mph compared to the same vehicle traveling at 60 mph?

The kinetic energy in the faster case is 4X as much (since KE = (1/2) m*v^2). The brakes must do an amount of work that is equal to the original kinetic energy. The brakes exert the same force in either case, so the distace will be 4X as long for the faster case.