Elastic Collision: Isolated Systems & Conservative Forces

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Discussion Overview

The discussion centers on the concept of elastic collisions, specifically examining the conditions under which they occur, including the roles of isolated systems and conservative forces. Participants explore theoretical implications and seek real-world examples of such collisions.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant asserts that in an elastic collision, both momentum and kinetic energy are conserved, implying that only conservative forces act, thus requiring an isolated system to prevent energy loss from external forces.
  • Another participant suggests that if the collision occurs over a sufficiently short time, external forces can be neglected, as the impulse from these forces approaches zero.
  • A participant questions the feasibility of observing elastic collisions in reality, expressing difficulty in imagining any collision occurring in such a brief time frame.
  • One example provided is the collision of two electrons, which is proposed as a scenario where elastic collisions might be observed.

Areas of Agreement / Disagreement

Participants express differing views on the practicality of elastic collisions in real-world scenarios, with some questioning their existence and others providing theoretical examples. The discussion remains unresolved regarding the feasibility and occurrence of such collisions.

Contextual Notes

Participants have not fully addressed the assumptions regarding the isolation of systems or the definitions of elastic collisions, leaving some aspects of the discussion open to interpretation.

sauri
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In an elastic collision both momentum and kinetic energy are conserved which means only conservative forces are acting (therefore no friction!).
So that must mean we also have to be in an isolated system, so no energy is lost due to external forces. Can this state actually exist in reality?. Any examples?.
 
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If the collision takes place in a short enough time, outside forces can be neglected. The impulse due to an outside force is Fdt-->0 as dt-->0.
The force between the two colliders is impulsive in that Fdt is finite.
 
any examples where we might see elastic collision happening? I can not imagine any collision happening in such a small period of time
 
Two electrons colliding.
 

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