Impact

Article By:

Barger, Vernon D. Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin.

Last reviewed:September 2021

DOI:https://doi.org/10.1036/1097-8542.339000

Show previous versions

• Impact, published August 2020:Download PDF Get Adobe Acrobat Reader

A force which acts only during a short time interval but which is sufficiently large to cause an appreciable change in the momentum of the system on which it acts. An impact is often studied in the context of the collision between two bodies. In the case of an impact, the collision is brief but significant in that the momenta of one or both bodies are altered in an appreciable, measurable, relevant manner. Speed and direction—that is, velocity—of the two bodies, as well as their respective masses, conformations, and compositions, are main factors in calculating the magnitude of an impact. These factors are also important if modeling the impact's subsequent effect on the behavior of the bodies, along with the system in which the bodies are situated (though of course other factors, such as external forces acting upon a system, can also be highly significant). An example of a major impact is a sharply struck billiard ball momentarily striking a second billiard ball and impelling the second ball into motion (see illustration). An example of minor impact is a lightly struck billiard ball colliding with a second billiard ball and inappreciably moving the second ball from its rest position. See also: Classical mechanics; Collision (physics); Force; Mass; Motion; Speed; Time; Velocity

The content above is only an excerpt.