A car with the weight 1200kg rolls down with the engine shut off, a hill with the slope 3 degrees and keeps a constant speed of 80 km/h on flat ground .75 liter petrol per 10km is consumed at this speed. The density of petrol is .80g/cm 3 and the energy content is 44mj/kg. how big is the power engine that generated at 80km/h on flat ground?