What Are the Algebraic Mysteries in Energy-Momentum-Mass Relations?

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Discussion Overview

The discussion revolves around the algebraic manipulations related to the energy-momentum-mass relations in the context of relativistic physics. Participants explore the implications of various equations and seek to identify errors in the algebra presented by a professor during a class.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents a series of algebraic transformations related to the relativistic energy-momentum relation, questioning the validity of the steps taken.
  • Another participant suggests that the clarity of the algebra could be improved with the use of parentheses.
  • A third participant expresses intrigue at the algebraic manipulation, indicating that it is an interesting approach.
  • A later reply acknowledges a mistake in the original algebra and expresses relief at having identified it, while also apologizing for any perceived confusion.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correctness of the algebraic manipulations, and there remains uncertainty regarding the validity of the steps taken in the calculations.

Contextual Notes

There are limitations in the clarity of the algebra presented, and the discussion does not resolve the mathematical steps or assumptions made throughout the thread.

Bazinga101
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<<Mentor note: Please always use descriptive thread titles.>>

First of all, the title is such that it attracts most views.You see, in class our professor did some goofing around numbers and variables in the relativistic energy momentum relation:
E2=(pc)2+m02c4
Since the energy required to accelerate an object to a certain velocity is
E=m0c2/√1-v2/c2,
∴E2=m02c4/1-v2/c2
plug in the value of E2,
p2c2+m02c4=m02c4/1-v2/c2
cancel out the m02c4
so p2c2=1/1-v2/c2
since c2= E/m,
⇒Ep2/m=1/1-v2/c2\
But, p2/m = 2* K.E and since E in E=mc2 implies any form of energy,and the object gains kinetic energy through it's motion, so Ek=E
⇒E(2E)=1/1-v2/c2
⇒2E2=1/1-v2/c2
⇒E2=1/2(1-v2/c2)
⇒E2=1/2-v2/c2
⇒E=1/√2-v2/c2
and that's it.No one in the room could figure out what's wrong, but our prof. said that something is wrong, but it is our job to find it out, plus, immediately one notices that if v=c, E=1 J. WTH!
 
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This might actually be readable if you put in some parentheses.
 
Bazinga101 said:
p2c2+m02c4=m02c4/1-v2/c2
cancel out the m02c4
so p2c2=1/1-v2/c2
That's... an interesting piece of algebra you did there.
 
Bandersnatch said:
That's... an interesting piece of algebra you did there.
Thanks Bandersnatch, i finally find out the mistake he did, and sorry for sounding stupid
 

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