Why Is Momentum Conserved but Not Kinetic Energy in an Inelastic Collision?

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Discussion Overview

The discussion revolves around the conservation of momentum versus the non-conservation of kinetic energy in inelastic collisions, exploring the underlying principles and definitions related to these concepts.

Discussion Character

  • Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants propose that momentum is conserved due to the symmetry in Newton's Third Law, while kinetic energy is not conserved because it can transform into other forms of energy such as heat or sound.
  • Others argue that inelastic collisions are specifically defined by the non-conservation of kinetic energy, contrasting with perfectly inelastic collisions where objects stick together, resulting in maximum kinetic energy loss.
  • A participant notes that while kinetic energy is converted into other energy forms, momentum remains present before and after the collision.
  • One participant expresses clarity on the topic after the discussion.

Areas of Agreement / Disagreement

Participants generally agree on the principle that momentum is conserved while kinetic energy is not in inelastic collisions, but the discussion includes varying explanations and definitions regarding these concepts.

Contextual Notes

The discussion does not resolve the nuances of definitions for inelastic and perfectly inelastic collisions, nor does it address the implications of energy transformation in detail.

bolbol2054
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why although the equations of momentum and kinetic energy of an object contains the same symbols m and v we note in an inelastic collision that momentum unlike the kinetic energy is conserved
 
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Momentum will always be conserved because of the symmetry regarding Newton III. But kinetic energy does not need to be conserved because it can easily be transformed into heat, sound, deformation, etc. Note that the total energy still is conserved, just not kinetic energy. Moreover, inelastic collisions are defined by us to be a collision which does not conserve kinetic energy much like perfectly inelastic collisions are defined to be a collision where the final two objects "stick" together resulting in the maximum loss in kinetic energy.
 
The kinetic energy is converted into other forms of energy. It all starts or ends with the motion of the body.

The momentum, whereas, is always there, before collision, after collision.
 
that's now clear thank you
 

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