The normal force causes a normal stress and the tangential force is responsible for a tangential, or shear, stress acting on the surface.
Shear forces cause contiguous parts of a structure or liquid to slide relative to each other.
Unifying Concepts and Processes Electrophoresis is the separation of a substance based on the electrical charge of the molecule and its motion in an applied electric field. An exception to the standard combustion process is hypergolic combustion. In this situation, a fuel and an oxidizer spontaneously react on contact without the need for an ignition stimulus. The jets used to maintain and change the Shuttle's orientation when in orbit are powered by hypergolic reactions. The creation and use of mathematical models is a key element of science, engineering, and technology.