Starting from rest, a horse pulls a 250 kg cart for a distance of 1.5 km. It reaches a speed of 0.38 m/s by the time it has walked 50.0 m and then walks at constant speed. The frictional force on the rolling cart is a constant 260 N. Each gram of oats the horse eats releases 9.0 kJ of energy; 10.0% of this energy can go into the work the horse must do to pull the cart. How many grams of oats must the horse eat to pull the cart?