What type of force is shear?

Shear is defined as a type of force that acts parallel to a surface. This force causes layers of material to slide past one another, creating a distortion in the material's shape without changing its volume. In practical terms, shear forces are commonly experienced in scenarios such as cutting, where one surface effectively 'slides' against another.

When understanding shear forces, it's important to visualize situations like scissors cutting through paper or tectonic plates sliding past each other, which exemplifies how shear forces operate. This distinguishes shear from other forces, such as normal forces, which act perpendicular to surfaces.