When a beam is subjected to different loads, such as weight, pressure, or other external forces, internal forces are generated within the beam. These forces can have a significant impact on the overall stability and strength of the structure. Engineers use various methods to analyze and determine the magnitude and direction of these internal forces. One common technique used to determine internal forces in beams is the method of sections. This method involves considering an imaginary point or section on the beam and analyzing the forces acting on that specific point.

The normal force, also known as the axial force, is the internal force that acts perpendicular to the cross-section of the beam. This force can be either compressive or tensile, depending on the nature of the load applied to the beam. Meanwhile, the shear force is the internal force that acts tangentially to the cross-section of the beam. Shear forces work in opposite directions on each segment of the beam. Normal and shear forces can be determined by applying the equilibrium equations to the beam under consideration.

Understanding normal and shear forces is crucial in structural engineering, as these forces play a significant role in determining the stability, strength, and overall performance of beams and other structural elements. Using the method of sections and equilibrium equations, engineers can accurately determine the internal forces within beams and design structures that can withstand the loads and stresses encountered during their service life.