Extensive testing of an experimental 2000-lb automobile reveals the aerodynamic drag for...

Extensive testing of an experimental 2000-lb automobile reveals the aerodynamic drag force F_D and the total nonaerodynamic rolling-resistance force F_R to be as shown in the plot. Determine (a) the power required for steady speeds of 30 and 60 mi/hr on a level road, (b) the power required for a steady speed of 60 mi/hr both up and down a 6-percent incline, and (c) the steady speed at which no power is required going down the 6-percent incline.