Hobbes pushes Calvin on a sled, which is traveling at a constant velocity on a flat field. The coeficient of kinetic friction between the sled and the snow is 0.200 and the combined mass of Calvin and the sled is 40.0 kg. Hobbes pushes on Calvin at an angle that is 12 degrees below the horizontal. Neglect air resistance.
What is the magnitude of force with which Hobbes pushes calvin.