The restitution coefficient is a dimensionless quantity that characterizes the different types of collision existing between two bodies. It is determined by the relationship between the speeds of the bodies involved immediately before and after the collision. Through the refund coefficient, we can understand if there was conservation total or partial of kinetic energy and even if it was totally dissipated.
Definition of the refund coefficient (e):
The refund coefficient is defined as the ratio of the relative speed of approach, immediately before the collision, and the relative speed of retreat, immediately after the collision.
Interpreting restitution coefficient values
Perfectly elastic collision:
THE perfectly elastic bump it is characterized by the total conservation of kinetic energy. Thus, the relative speed of approach and departure of the furniture involved in the collision will be equal and, therefore, for this type of collision, the restitution coefficient will assume a value equal to 1.
e = 1
Partially elastic collision:
THE partially elastic collision it is characterized by the partial loss of kinetic energy, mainly dissipated by the sound and heat generated at the moment of the collision. In this case, the relative speed of approach will be greater than the relative speed of retraction and, therefore, the value of the restitution coefficient will be between 0 and 1.
0 < and < 1
Inelastic collision:
THE inelastic collision it is characterized by the fact that, after its occurrence, the bodies involved remain together. Therefore, there will be no relative retraction speed and, therefore, the refund coefficient will be nil. In this type of collision, there is maximum loss of energy.
e = 0
The table below helps to understand the relationship between restitution coefficient and collisions:
Note that the amount of movement is always conserved, regardless of the type of collision.
By Joab Silas
Graduated in Physics
Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/fisica/o-que-e-coeficiente-restituicao.htm
