A vehicle is stuck on the railroad tracks as a 30*10^6 lb train is approaching with a speed of 75mph. As soon as the problem is detected, the train's emergency brakes are activated, locking the wheels and causing the locomotive to slide. If the coefficient of kinetic friction between the train and the track is 0.45, what is the minimum distance d at which the brakes must be applied to avoid a collision? Treat the train as a particle and assume that the railroad tracks are rectilinear and horizontal.