Not sure about the correct wording for this question! A brick of mass M sits on a rubber pillow of mass m . Together they are sliding to the right at constant velocity on an ice-covered parking lot. (a) Draw a free-body diagram of the brick and identify each force acting on it. (b) Draw a free-body diagram of the pillow and identify each force acting on it. (c) Identify all the action-reaction pairs of forces in the brick-pillow-planet system. Assume the brick is m1 and the pillow is m2 For a), the brick should have an upward force and Fg downward. Should the upward force be F21 or n or both? For b), the pillow should have a normal force upward, force due to gravity downward, and a downward force (F12?).