Kinetic energy changes in collisions

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SUMMARY

The coefficient of restitution (COR) is a critical measure in collision physics, representing the ratio of relative velocities of two particles before and after a collision, rather than the percentage of kinetic energy retained. A COR of 1 indicates a perfectly elastic collision with no kinetic energy loss, while a COR of 0 signifies a perfectly inelastic collision where particles stick together and lose all kinetic energy. To determine the percentage of kinetic energy retained, one must apply the conservation of momentum and conservation of kinetic energy equations, taking into account the masses and velocities of the colliding particles.

PREREQUISITES
  • Understanding of the coefficient of restitution (COR)
  • Knowledge of conservation of momentum principles
  • Familiarity with conservation of kinetic energy equations
  • Basic grasp of elastic and inelastic collisions
NEXT STEPS
  • Study the mathematical derivation of the coefficient of restitution
  • Learn how to apply conservation of momentum in collision scenarios
  • Explore examples of elastic and inelastic collisions in real-world applications
  • Investigate the relationship between COR and energy loss during collisions
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Physics students, educators, and professionals in engineering or mechanics who seek to deepen their understanding of collision dynamics and energy conservation principles.

Jacob Aron
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Is the coefficient of restitution of two particles a measure of the percentage of kinetic energy retained after a collision? My textbooks and Google are no help. If it isn't, what is it a percentage of?
 
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The coefficient of restitution (COR) is not a measure of the percentage of kinetic energy retained after a collision. It is a measure of the ratio of the relative velocities of two particles before and after a collision.

In other words, the COR is a measure of the elasticity of a collision. A COR of 1 indicates a perfectly elastic collision, where the two particles bounce off each other with no loss of kinetic energy. A COR of 0 indicates a perfectly inelastic collision, where the two particles stick together after the collision and all kinetic energy is lost.

The COR is not a percentage, but rather a decimal or fraction. For example, a COR of 0.5 means that the relative velocity after the collision is half of the relative velocity before the collision.

To calculate the percentage of kinetic energy retained after a collision, you would need to know the masses and velocities of the particles before and after the collision. This can be calculated using the conservation of momentum and the conservation of kinetic energy equations.

In summary, the coefficient of restitution is not a measure of the percentage of kinetic energy retained after a collision, but rather a measure of the elasticity of the collision. The percentage of kinetic energy retained can be calculated using the conservation laws.
 

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