Car A weighing 4000 lb and car B weighing 3700 lb are at rest on a flatcar which is also at rest. Cars A and B then accelerate and quickly reach constant speeds relative to the flatcar of 7.65 ft/s and 7.50 ft/s, respectively, before decelerating to a stop at the opposite end of the flatcar. Knowing that the speed of the flatcar is 1.02 ft/s when the cars are moving at constant speeds, determine the weight of the flatcar. Neglect friction and rolling resistance.