What does a bending moment represent at a point in a beam?

A bending moment at a point in a beam represents the internal moment generated in response to external forces or loads acting on the beam. This moment arises from the tendency of those forces to cause the beam to rotate about that point. When loads are applied to a beam, they induce stresses that cause bending, and the bending moment quantifies that effect.

The bending moment is particularly important in structural analysis because it helps engineers determine how the structure will perform under various loading conditions. An understanding of bending moments is crucial when designing beams to ensure they can support the applied loads without failing.

In this context, the other choices do not accurately encapsulate what a bending moment represents. For instance, the vertical load alone does not take into account how the beam might bend or resist those loads. The total resistance to movement does not specifically relate to the moment caused by loads, while the overall weight of the beam is a factor that can affect loading but does not encompass the idea of a bending moment, which is specifically related to how forces induce rotational effects at points along the beam.