Mechanical Engineering - Engineering Mechanics - Discussion

The coefficient of restitution (COR) of two colliding objects is a fractional value representing the ratio of speeds after and before an impact, taken along the line of the impact.

What is coefficient of restitution?

Can anyone explain clearly regarding the difference of elastic bodies and elastic collision. I think then it will be clear to differentiate between the coefficients.

The difference between elastic & perfectly elastic body is if the body is perfectly elastic then the value of e is 1.

Coefficient of restitution is a thing which will be experienced only when the bodies collide with each other and for a perfect elastic collision we need elastic bodies. Therefore this answer is wrong and e=1 for elastic bodies.

What is elastic body?

A body which can regain its original shape and size after removing the load (if load cause deformation in body) is called elastic body.

A bouncing basketball captured with a stroboscopic flash at 25 images per second. Ignoring air resistance, the square root of the ratio of the height of one bounce to that of the preceding bounce gives the coefficient of restitution for the ball/surface impact.

The coefficient of restitution (COR) of two colliding objects is a fractional value representing the ratio of speeds after and before an impact, taken along the line of the impact. Pairs of objects with COR = 1 collide elastically, while objects with COR < 1 collide inelastically. For a COR = 0, the objects effectively "stop" at the collision, not bouncing at all. An object (singular) is often described as having a coefficient of restitution as if it were an intrinsic property without reference to a second object, in this case the definition is assumed to be with respect to collisions with a perfectly rigid and elastic object. COR = (relative speed after collision) / (relative speed before collision). The mathematics was developed by Sir Isaac Newton in 1687.

The coefficient of restitution for elastic bodies is ZERO.

COR=1 for elastic collision not elastic bodies.