3. (5 points) A small experimental vehicle has a total mass m of 450 kg including wheels and driver. Each of the four wheels has a mass of 45 kg and a centroidal radius of gyration of 425 mm. Total frictional resistance R to motion is 450 N and is measured by towing the vehicle at a constant speed on a level road with engine disengaged. Determine the power output of the engine for a speed of 70 km/h up the 10 percent grade (a) with zero acceleration and (b) with an acceleration of 4 m/s. Hint: Power equals the time rate of increase of the total energy of the vehicle plus the rate at which frictional work is overcome). 10 1200 mm