Perfectly Inelastic and initial kinetic energy

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Homework Help Overview

The discussion revolves around a perfectly inelastic collision involving two objects of different masses, where one object is initially at rest. The focus is on determining the fraction of initial kinetic energy lost during the collision.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to apply conservation of momentum and kinetic energy principles to analyze the collision. Some participants question the correctness of the initial setup and calculations, while others suggest considering the ratio of final to initial kinetic energy.

Discussion Status

The discussion is ongoing, with participants exploring different aspects of the problem. Some guidance has been provided regarding the need for a ratio factor in the equations being used, but there is no explicit consensus on the correctness of the approach yet.

Contextual Notes

Participants are working within the constraints of a homework problem, which may limit the information available for a complete analysis. The discussion includes assumptions about the nature of the collision and the definitions of kinetic energy involved.

jan2905
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An object of mass m (O1) moving with speed v collides head-on with a target object of mass 2m (O2) initially at rest. If the collision is perfectly inelastic, what fraction of O1's initial kinetic energy is lost?



1/2(m1)v^2initial=1/2(m1+m2)v^2final

m1v1=(m+2m)v2

v2=1/3(v1)

so...

1/2(m1)v^2=1/2(m1+m2)(1/3*v)^2 ... is this right so far?
 
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Take the ratio of the final kinetic energy to the initial kinetic energy. These two are not equal to each other unless you include a ratio factor on the left side of the equation.
 
1/3? 3m*(1/9)v^2 yields a factor of 1/3.
 
Correct.
 

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