Workers pushing a 180 kg trunk across a level floor encounter a 10 m long region where the floor becomes increasingly rough; the coefficient of kinetic friction increases from mo =.17 to .79 according to the expression (mk = mo + ax2) where a= 0.0062 m-2, and x is the distance in meters from the beginning of the rough region. How much work does it take to push the trunk at constant speed across the region?