The fully-loaded tractor-trailer drives up a 3% incline at a steady speed of 70 km/h (45 mph). The frontal area of the tractor-trailer is 2.59 m (102 in.) wide and 4.11 m (13.5 ft) high, and it is powered by a 500-hp engine. The total weight of the tractor-trailer and its payload is approximately equal to the legal limit of 355 kN (80 000 lb). It is estimated that the coefficient of rolling resistance is 0.008, and the drag coefficient is 0.6. What power must be supplied by the engine to overcome the resistance to motion caused by the weight, rolling resistance, and aerodynamic drag? What percentage of the rated engine power is required to overcome these effects? Assume standard air. Rolling resistance can be estimated as the normal force times the coefficient. ANS 291 kW, not given 70 km/h Slope =3%