What is the Coefficient of Restitution and How can it be Measured? The physical laws of nature determine the impact of every action and reaction taking place between any two bodies. In terms of collision between two or more bodies, the Coefficient of Restitution (COR) is the variable that indicates the range and impacts any collision they can produce. It is basically a ratio of the final and initial relative velocity of colliding objects after their impactful interaction. In theoretical calculations, it usually ranges between 0 and 1, where 1 indicates a perfectly elastic collision.
However, in general observations, the COR value is always less than 1 because initial translational kinetic energy is lost to rotational kinetic energy, plastic transformations, and the production of heat. The coefficient of restitution tester is designed on the basis of the four methods discovered by scientists to calculate COR value for objects. These four methods can be enumerated as follows: Ballistic Method This method was invented by C.V. Boys and stands as the most practically viable method for calculating the coefficient of restitution for objects. It is applied for testing the COR of baseballs in their manufacturing industries. In this device, a projectile is shot towards a heavy wooden block. After the collision, the projectile becomes embedded on it and the pendulum block starts swinging at a certain speed. The height and swing angle of the pendulum is used to determine the COR after some theoretical calculations. The coefficient of restitution tester designed on the basis of this method considers the momentum, kinetic energy, and gravitational force for calculating the COR.