Answer:
a. The free body diagram for this object has been attached. It shows all the forces acting on the body at rest, including the friction force in the opposite direction to sliding of the object (assume it's left to right).
b. Since the object is in contact with the surface, there is a normal force acting on both of them and is equal to the weight exerted by each. This perpendicular force is defined by Newton's second law of motion.
c. The force of friction always acts in a direction opposite to the direction of motion of the body. F = mg ('a' for acceleration is replaced by 'g' gravity because acceleration in this case is just gravity).
Hope that answers the question, have a great day!
