Final answer:
The provided excerpts do not directly answer the question about scaffold plank extension. Scaffold planks should not extend less than 6 inches nor more than 12 inches beyond their end supports, as per general safety regulations.
Step-by-step explanation:
The question regarding the minimum and maximum distances that a scaffold plank can extend beyond its end support does not provide a direct answer within the provided context. Typically, safety regulations such as those from the Occupational Safety and Health Administration (OSHA) in the United States indicate that scaffold planks should not extend less than 6 inches (15 cm) and no more than 12 inches (30 cm) beyond their end supports when not secured. The precise values can vary based on local regulations and specific scaffold design.
However, the provided excerpts do not align with this inquiry and seem to be related to physics problems involving tension in cables supporting a scaffold, measurements conversion from inches to centimeters, and historical context regarding the stowing of slaves, which are unrelated to the original question about scaffold planks.