Two boxes of mass 6.10 and 5.00 kg are in contact and are accelerated across a horizontal surface by an force of 43.17 N applied parallel to the surface and pushing on the lighter box. The magnitude of the frictional force between the surface and the lighter mass is 6.62 N and between the surface and the heavier mass is 12.55 N. Find the acceleration of the two boxes. Find the magnitude of the force exerted by the lighter box on the heavier box. What is the magnitude of the force exerted by the heavier box on the lighter box?