Final answer:
The statement in the question is true; features like vanes and ribs are generally not crosshatched in sectional drawings to maintain clarity. Additionally, friction varies between different surfaces due to their relative roughness or smoothness. In cross-sections, the dip angle of contacts is important for accurately representing the orientation of layers.
Step-by-step explanation:
The statement, "True or False? Aligned or revolved features such as vanes, fins, spokes, lugs, and ribs are NOT crosshatched even if the cutting plane passes through them," is True. This practice is common in technical drawing and engineering to avoid visual clutter and to emphasize the primary elements of the cross-section. Features that are symmetrical and repeat, such as vanes and ribs, are typically not crosshatched in a sectional view because it is understood that they are cut through. The focus in cross-sections is often on illustrating the relationship and orientation of the different materials or components.
Friction indeed varies from surface to surface, reflecting the fact that surfaces have differing levels of roughness or smoothness. This is critical to understand in the context of engineering and physics since it impacts the performance and design of mechanical systems and interfaces between different materials.
An important feature on cross-sections is the dip of any contacts, such as strata or material layers. If the cross-section is constructed perpendicular to the strike of these dipping layers, then what is shown is the true dip. However, if the cross-section is oriented differently, it will show the apparent dip, which is less than the true dip.
Aligned or revolved features such as vanes, fins, spokes, lugs, and ribs are NOT crosshatched even if the cutting plane passes through them. This statement is true. Crosshatching is a method used to represent the intersection of a cutting plane with features in technical drawings. However, aligned or revolved features are usually shown using different conventions such as hidden lines or different line styles, rather than crosshatching.