In chapter 8 on page 182 in the procedure for drawing free body diagrams:
Procedure item 1 refers to the center of mass.
Suggestion 1: Don't mention CM at all.
Rationale: It seems to me the CM is irrelevant to the physics, because we are assuming one-dimensional motion of a rigid body.
Suggestion 2: Leave the CM symbol out of the force-vector diagram.
Rationale: In the FBD it is unnecessary and often unhelpful to draw the forces as "attached" to the CM or otherwise "attached" to the free body. It is important to remember that a vector has direction and magnitude, but it does not have a position. Therefore we are free to arrange the vectors on the diagram however we find convenient. For example,
Figure 8.6 would be more clear if the vectors were spread out horizontally.
if the body is at or near equilibrium, it may be convenient to arrange the forces as a vector addition problem, to display the net force more clearly. For example, here we have three forces that add up to zero:
In chapter 8 on page 182 in the procedure for drawing free body diagrams:
Procedure item 1 refers to the center of mass.
Suggestion 1: Don't mention CM at all.
Rationale: It seems to me the CM is irrelevant to the physics, because we are assuming one-dimensional motion of a rigid body.
Suggestion 2: Leave the CM symbol out of the force-vector diagram.
Rationale: In the FBD it is unnecessary and often unhelpful to draw the forces as "attached" to the CM or otherwise "attached" to the free body. It is important to remember that a vector has direction and magnitude, but it does not have a position. Therefore we are free to arrange the vectors on the diagram however we find convenient. For example,
See #90 for a catalog of related issues.