A two-engine jet transport has a loaded weight of 90,000 lb and a forward thrust of 9800 lb per engine during takeoff. If the transport requires 4800 ft of level runway starting from rest to become airborne at a speed of 140 knots (1 knot = 1.151 mi/hr), determine the average resistance R to motion over the runway length due to drag (air resistance) and mechanical retardation by the landing gear.