Coefficient of restitution factors

[DV10]

Homework Statement

On what all factors does coefficient of restitution depend?i mean do we have 1 for a pair of surfaces in contact or a surface has one irrespective of the surface of the other colliding body?Also,practically,does coefficient of restitution change/vary?If yes,could anyone please
specify the dependency on various factors?Lastly,taking the example of a ball and the floor,lets say if I keep dropping the ball on the floor in simultaneous but "different"(ie i let the ball bounce only once)experiments,will the coefficient of resitution reamain same for all experiments(practically and considering a very large number,say of the order of 10 to the power 100 or so,of the same experiment,ie letting the ball bounce once after dropping it from the same height)

Homework Equations

e=(v2-v1)/(u2-u1)

The Attempt at a Solution

couldnt infer much from the eqn given above..

 

[jtyler05si]

From what I have experienced they either gave me the coefficient for the particular case and asked me to find a velocity in some direction and/or at a certain time; or they gave me information and asked me to find the coefficient.

So given that I think the coefficient of restitution is entirely based off of recorded velocity results between two materials/objects. Much like friction coefficients, it is based off of what is making contact with what.
I imagine in the real world you can't assume the coefficient of restitution out of a textbook for a basketball on a wood floor applies to all basketballs. It probably was only applicable to the test ball at a certain pressure, and a million other constraints. It is a good average but if your basketball is just a hair under-pressure it makes a huge difference, we have all seen this.
And for the "simultaneously dropping the balls in different places": I would say it would be the same, IF the balls were the same in the same conditions and hitting the same surfaces with the same conditions. But the answer is no if one is hitting concrete while one is hitting wood, etc.

I hope that helps and I am sure someone will chime in with a much more technical explanation rather than my example driven ramblings.

 

[DV10]

well what I'm actually looking for is practical variations with conditions.I'm building a project which works on collisions n so i want to know for how long will my original calculations be valid and what all variations will occur with time.still,i appreciate your response.

 

[DV10]

anyone?moderators?please help.

 

[rdl]

The coefficient of restitution is a measure of the elasticity of a collision between two objects. It depends on several factors, including the materials of the objects, the surface conditions, and the relative velocities and masses of the objects. It is not a fixed value for a pair of surfaces, but rather it can vary depending on these factors.

In practical situations, the coefficient of restitution can change or vary due to changes in these factors. For example, if the surface of the objects changes (such as becoming rougher or smoother), the coefficient of restitution may change. Similarly, if the objects are made of different materials or have different masses, the coefficient of restitution may also change.

In the specific example of a ball and the floor, the coefficient of restitution will depend on the materials of the ball and the floor, the surface conditions, and the height from which the ball is dropped. It is possible that the coefficient of restitution may be the same for multiple experiments with the same conditions, but it is not guaranteed. In fact, in most practical situations, the coefficient of restitution will vary to some degree.

It is important to note that the coefficient of restitution is not a constant value, but rather a measure of the energy lost in a collision. Therefore, it is not necessary for the coefficient of restitution to remain the same for all experiments, even if they are done under the same conditions. It is also unlikely that one would be able to conduct 10 to the power of 100 experiments with the exact same conditions, so it is not possible to say whether the coefficient of restitution would remain the same in this scenario.