Shear Stress

physics · forces · materials

Sideways squishing force. Shear stress happens when a force pushes or pulls parallel to a surface, rather than straight into it. Imagine sliding one hand over the other with pressure, that's shear stress at work.

Different from normal stress. Normal stress pushes straight down into a material, like standing on a bridge. Shear stress pushes sideways across it, like trying to slide that bridge sideways underneath you.

Shows up everywhere. Shear stress affects how scissors cut paper, how a piece of wood splits, and how tall buildings sway in the wind. Engineers have to carefully calculate shear stress to make sure buildings and bridges stay safe.

Makes materials weaker. Shear stress is often the reason materials fail or break before other types of stress would damage them. It's why a rope frays when you twist it hard, or why a table might snap if you try to bend it sideways.

Measured in pascals. Scientists measure shear stress using the same units as regular pressure, called pascals. The stronger the shear force and the smaller the area, the higher the shear stress.