Inelastic collisions with constant momentum

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Homework Help Overview

The discussion revolves around the topic of inelastic collisions, specifically focusing on the conservation of momentum and kinetic energy calculations. Participants are examining the implications of the wording in a textbook regarding the objects involved in the collision.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the calculation of kinetic energy before a collision and whether the interpretation of the problem aligns with the textbook's wording about the objects involved. There is a focus on the distinction between "identical objects" and "objects of the same mass."

Discussion Status

The discussion is exploring various interpretations of the textbook's language, with some participants expressing agreement on the calculations while others are raising questions about the assumptions made regarding the objects in the problem. There is no explicit consensus, but the dialogue is productive in examining the nuances of the problem.

Contextual Notes

Participants note potential discrepancies in the textbook's wording and its implications for understanding the problem, particularly regarding the specification of the objects involved in the collision.

haha0p1
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Homework Statement
The total momentum before the collision in an inelastic collisions is 0, but the total kinetic energy before the collision is 1/2mv². Calculate how the total kinetic energy before collision is 1/2mv².
Relevant Equations
Ek=1/2mv²
Kinetic energy before collision =1/2 mv² + 1/2 mv² = mv² (since energy is a scalar quantity, the direction does not matter). Kindly tell why am I not getting the required answer i.e: 1/2 mv². Am I doing the calculation wrong?
IMG_20230102_154827.jpg
 
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Hi,

I agree with your calculation. An unfortunate error in the book.

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It's interesting that the book specifies the "same object" or "identical" objects, where all that is required kinematically is objects of the same mass!
 
PeroK said:
It's interesting that the book specifies the "same object" or "identical" objects, where all that is required kinematically is objects of the same mass!
Truee
 
PeroK said:
It's interesting that the book specifies the "same object" or "identical" objects, where all that is required kinematically is objects of the same mass!
I think it's economy of words. "Identical objects" is shorter than "objects of the same mass" and conveys the idea of symmetry. "Identical" becomes relatively conciser when the masses also carry equal charges.
 
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PeroK said:
It's interesting that the book specifies the "same object"
No, it says "the same two objects". Presumably the same two as in the preceding question.
 

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