What is the Difference Between Elastic and Perfectly Elastic Collision?

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The difference between elastic and perfectly elastic collisions lies in the conservation of energy and the change in kinetic energy during the collision. Here are the key differences:

  • Elastic Collision: In an elastic collision, there is no net loss in kinetic energy in the system as a result of the collision. Both momentum and kinetic energy are conserved quantities in elastic collisions. However, in reality, there are no perfectly elastic collisions because kinetic energy always tends to convert into other forms of energy, such as noise or potential energy. Examples of near-elastic collisions include collisions between atoms in gases and collisions between rigid billiard balls.
  • Perfectly Elastic Collision: A perfectly elastic collision is an ideal situation where there is no net conversion of kinetic energy into other forms of energy, such as noise or potential energy. In this type of collision, the total kinetic energy of the system remains the same before and after the collision. Perfectly elastic collisions do not exist in real life, but they are useful as a theoretical concept to help solve problems in mechanics.

In summary, while both elastic and perfectly elastic collisions involve the conservation of momentum and kinetic energy, a perfectly elastic collision is an idealized situation where there is no net change in kinetic energy, whereas an elastic collision is a more realistic scenario where the change in kinetic energy is negligible.

Comparative Table: Elastic vs Perfectly Elastic Collision

Here is a table summarizing the differences between elastic and perfectly elastic collisions:

Feature Elastic Collision Perfectly Elastic Collision
Energy Conservation Kinetic energy is conserved, but some energy may be converted into other forms, such as sound or heat energy. Kinetic energy and momentum are conserved, and there is no net conversion of energy into other forms, such as heat or noise.
Momentum Conservation Momentum is conserved. Momentum is conserved.
Real-world Occurrence More common in real-world scenarios, such as collisions between atoms or small objects. Highly unlikely in the real world, as there is almost always a change in energy.
Examples Collisions between small bodies, like atoms, or cases where objects bounce back without generating heat or undergoing deformation. Swinging balls or a spacecraft flying near a planet without getting caught in its gravity.

In summary, elastic collisions involve a negligible change in total kinetic energy and the conservation of momentum, while perfectly elastic collisions represent an ideal case where kinetic energy, momentum, and total energy are all conserved. Elastic collisions are more common in real-world scenarios, whereas perfectly elastic collisions are highly unlikely to occur.