Prallung

Prallung is a term used in physics and engineering to describe the rebound or deflection of a moving object or wave after it strikes a surface or obstacle. The concept covers a range of phenomena, from a ball bouncing on the ground to the reflection of sound or light at a boundary.

In mechanics, Prallung is analyzed with the coefficient of restitution typically denoted e, the ratio of rebound speed to incident speed along the normal to the contact surface. A value of e = 1 denotes a perfectly elastic rebound with no energy loss, while 0 < e < 1 indicates partial energy loss through deformation, heat, or sound. The trajectory after impact depends on incident angle and surface properties.

In acoustics and optics, Prallung describes the reflected wave. On smooth surfaces the reflection follows the law of reflection, with the angle of incidence equal to the angle of reflection. On rough or heterogeneous surfaces the reflection can become diffuse, distributing energy in several directions.

Surface characteristics such as roughness, material stiffness, and damping, as well as impact velocity and angle, govern the extent of Prallung. The term is used across disciplines, often alongside related notions such as reflection, impulse, and energy transfer.

See also: reflection, coefficient of restitution, elastic collision, diffraction, echo.