Deflection (physics)

A deflection, in physics, refers to the change in an object's velocity as a consequence of contact (collision) with a surface or the influence of a field. Examples of the former include a ball bouncing off the ground or a bat; examples of the latter include a beam of electrons used to produce a picture, or the relativistic bending of light due to gravity.
Deflective efficiency.
An object's deflective efficiency can never equal or surpass 100%, for example:
This transfer of some energy into heat or other radiation is a consequence of the theory of thermodynamics, where, for every such interaction, some energy must be converted into alternative forms of energy or is absorbed by the deformation of the objects involved in the collision.