Coefficient of Restitution

However, for a simulation like this, you could use a lookup table or some other predefined method to determine the coefficient of restitution based on the types of objects colliding. This would allow for arbitrary coefficients of restitution while still maintaining realistic collisions.
  • #1
Falmarri
6
0
I'm working on a software project that simulates spheres colliding in free space. We were thinking of having the coefficient of restitution different for each sphere (arbitrarily or randomly assigned at run time) but I forgot that the coefficient of restitution depends on the collision, not the object (physics was 4 years ago =P ). We could easily just have different types of objects (as in wood, metal, etc) and have definitions of coefficients between all the various types, but I'm still determined to have it be able to be arbitrary. Is there a way I can do this? Is there some formula that let's you know what the coefficient of restitution would be for a collision between 2 objects if you know, say, what the coefficient of restitution would be for each object against something whose coefficient is 1?

Thanks
 
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  • #2
In general, no. Much like coefficient of friction, this is something that needs to be experimentally measured.
 
  • #3
for reaching out for clarification on the coefficient of restitution, or COR. As you mentioned, the COR is a measure of how much energy is lost during a collision between two objects. It is a unitless value that ranges from 0 (perfectly inelastic collision with no bounce) to 1 (perfectly elastic collision with full bounce).

In terms of your software project, it is possible to assign different coefficients of restitution to each sphere, but it would require some additional calculations and considerations. The COR for a collision between two objects is not simply the average of their individual CORs. It also depends on the relative masses and velocities of the objects before and after the collision.

One approach you could take is to use the coefficient of restitution as a variable that can be adjusted within your simulation. This would allow you to have different CORs for each sphere, but still have the correct calculations for each collision based on the objects' properties and the laws of physics.

Alternatively, you could create a database or table that defines the COR for each combination of objects (e.g. wood-wood, wood-metal, metal-metal, etc.). This would require more initial setup, but would provide more accurate and consistent results.

Overall, it is possible to have varying coefficients of restitution in your simulation, but it will require some careful consideration and implementation to ensure accurate and realistic collisions. I recommend consulting with a physics expert or doing further research on the topic to determine the best approach for your project.
 

What is the Coefficient of Restitution?

The Coefficient of Restitution is a measure of the elasticity of a collision between two objects. It is a dimensionless number that ranges from 0 to 1, with 1 representing a perfectly elastic collision and 0 representing a completely inelastic collision.

How is the Coefficient of Restitution calculated?

The Coefficient of Restitution is calculated by taking the ratio of the relative velocity of the objects after the collision to the relative velocity before the collision. This can be expressed mathematically as e = (vf - vi) / (ui - uf), where e is the Coefficient of Restitution, vf and vi are the final and initial velocities of the objects respectively, and ui and uf are the initial and final velocities of the objects in the opposite direction.

What factors affect the Coefficient of Restitution?

The Coefficient of Restitution is affected by a number of factors, including the material properties of the objects involved, the shape and surface roughness of the objects, and the angle and speed of the collision. The Coefficient of Restitution can also be affected by external factors such as air resistance and temperature.

Why is the Coefficient of Restitution important?

The Coefficient of Restitution is an important concept in physics and engineering, as it helps us understand and predict the behavior of objects in collisions. It is used in various fields such as sports, automotive engineering, and ballistics to optimize designs and improve safety.

What is the difference between a perfectly elastic and a perfectly inelastic collision?

A perfectly elastic collision is one in which the objects involved bounce off each other without any loss of energy, resulting in a Coefficient of Restitution of 1. In a perfectly inelastic collision, the objects stick together and move as one, with a Coefficient of Restitution of 0. In reality, most collisions fall somewhere in between these two extremes, with a Coefficient of Restitution between 0 and 1.

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