Kinetic energy changes in collisions

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The coefficient of restitution (COR) measures the elasticity of a collision, indicating the ratio of relative velocities of two particles before and after impact, rather than the percentage of kinetic energy retained. A COR of 1 signifies a perfectly elastic collision with no kinetic energy loss, while a COR of 0 indicates a perfectly inelastic collision where particles stick together and lose all kinetic energy. The COR is expressed as a decimal or fraction, not a percentage. To determine the percentage of kinetic energy retained, one must apply conservation of momentum and kinetic energy equations based on the masses and velocities of the colliding particles. Thus, the COR is essential for understanding collision dynamics but does not directly quantify kinetic energy retention.
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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