A tractor-trailer is traveling at 60 mi/h when the driver applies his brakes. Knowing that the braking forces of the tractor and the trailer are 3600 lb and 13,700 lb, respectively, determine (a) the distance traveled by the tractor-trailer before it comes to a stop, (b) the horizontal component of the force in the hitch between the tractor and the trailer while they are slowing down.