For Free-body-diagrams draw only the forces acting on the object in question.
Forces: 7 Newton's First Law:
For onjects at rest or moving at constant velocity the net force is zero.
Forces: 8 Newton's Second Law:
A net unbalanced force produces acceleration.
Forces: 9
The normal force and the gravitational force are not an action-reaction pair.
Forces: 10
Static friction exists between two surfaces when motion is impending; kinetic friction occurs when two surfaces are in relative motion. In either case, the friction forces are proportional to the normal force.
Forces: 11
For inclined planes, the minimum coefficient of static friction u=tan 0