Shear is defined as which of the following?

• A. A force causing rotation about the member's axis
• B. A force that resists bending
• C. A force resulting from equal but opposite transverse forces that tend to slide one section past an adjacent section
• D. A force acting along the length of the member

Answer: (C)

Shear is the internal force that acts parallel to the cross-section, created when equal and opposite transverse forces try to slide one part of a member past an adjacent part. This parallel-to-section force is what causes shear stress within the material.

That description matches what shear is: equal and opposite forces across a section trying to slide one side relative to the other. The other ideas don’t fit: a force that causes rotation about the member’s axis describes a moment (torsion/bending), not shear; a force that resists bending talks about bending moments rather than a force type; and a force acting along the length of the member is an axial (longitudinal) force, not shear.