In the context of beam bending, which force is primarily responsible for shear?

The primary force responsible for shear in the context of beam bending is distributed loads. When a beam is subjected to a distributed load, this load is spread over the length of the beam, creating varying internal shear forces.

Shear force occurs as a result of the way these distributed loads act upon the beam. Each segment of the beam experiences an upward reaction force from its supports, counteracting the downward force of the distributed load. The difference between the internal forces acting upward and the total load acting downward at any point along the beam creates shear forces. As the load is distributed across the entire length, it affects the internal shear flow rather than acting at a single point, leading to shear being particularly pronounced in beams subjected to such loads.

In contrast, point loads generate concentrated forces at specific locations along the beam, which can also result in shear but do not influence the shear distribution in the same way as distributed loads, which impact a larger area and create continuous variations in shear across the length of the beam.