Understanding the Equation E=mc^2 and Its Applications

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Homework Help Overview

The discussion revolves around the equation E=mc^2 and its applications, specifically addressing a problem related to the interpretation of energy and mass in different contexts, including kinetic energy and rest mass energy.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are questioning the correctness of various answer choices related to the problem, particularly focusing on why certain options are deemed incorrect and the rationale behind the correct answer. There is an exploration of the relationship between mass and energy, especially in the context of kinetic energy versus rest mass energy.

Discussion Status

The discussion is ongoing, with participants actively questioning the validity of their choices and seeking clarification on the reasoning behind the correct answer. Some guidance has been offered regarding the distinctions between different types of energy, but there is no explicit consensus on the interpretations of the answers.

Contextual Notes

Participants are operating under the constraints of a homework assignment, which may limit the information available for making determinations about the problem. There is an acknowledgment that additional information would be necessary to fully resolve the questions raised about the mass and energy relationships.

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Homework Statement


see attached question


Homework Equations





The Attempt at a Solution



I chose A but this is wrong :S - why?

The answer is C but I cannot see why B/D are wrong.
I literally guess A as this was the only time I had used the fomula
 

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A is wrong because, for example, a proton can have kinetic energy separate from its rest-mass energy.
 
Steely Dan said:
A is wrong because, for example, a proton can have kinetic energy separate from its rest-mass energy.

so why is C correct and B/D wrong?
 
jsmith613 said:
so why is C correct and B/D wrong?
First of all, I think A is wrong because there is no change in mass. B is wrong because you cannot determine the original mass of coal from just the rest mass of a proton and rest mass of an electron. You would have to have other information. Similarly with D you would cannot determine the energy from the rest masses of a proton or electron. You would have to know how fast the protons were moving before collision.

AM
 
thanks
 

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