Final answer:
Both parts of the student's statement are true. Shear force relates to the reaction from shear stress, while bending moment measures the total moment developed at a point due to external forces.
Step-by-step explanation:
The statement that shear force is a measure of the reaction at a given point to being sheared by external forces is true. Shear force is influenced by shear stress, which is due to forces acting parallel to a surface. The shear modulus (S) is used in tandem with the force applied (F) to determine the shear stress on a body. Specifically, the force F applied perpendicular to the object's original length (Lo) and parallel to the cross-sectional area (A) alongside the associated shear modulus can assess the deformations due to shearing.
In contrast, bending moment is indeed a measure of the total moment developed at a point by an external force, confirming the second part of the statement as true. The bending moment is influenced by the size and distribution of external loads, as well as the shape and constraints of the structure. It is a critical factor in understanding how structural elements behave under load, particularly in bending.