Inverse Funcation of Relativistic mass

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Discussion Overview

The discussion centers on the concept of the inverse function of the relativistic mass equation, exploring the relationship between relativistic mass, speed, and rest mass. Participants examine the implications of their interpretations and the algebraic manipulations involved in deriving an inverse formula.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant describes the relativistic mass equation and its relationship to speed, asserting that as speed approaches light speed, the relativistic mass decreases while rest mass remains constant.
  • Another participant provides the standard form of the relativistic mass equation and questions the initial claim about the relationship, suggesting that the mass actually increases with speed.
  • A participant points out potential algebraic errors in the proposed inverse equation, noting inconsistencies in units and suggesting that the inverse should be expressed in terms of velocity.
  • Another participant critiques the change in symbol meanings without clarification, providing an alternative expression for velocity derived from the relativistic mass equation.

Areas of Agreement / Disagreement

Participants express differing interpretations of the relativistic mass equation and its inverse, with no consensus reached on the correct formulation or meaning of the inverse function.

Contextual Notes

There are unresolved issues regarding the algebraic manipulation of the equations, the definitions of the symbols used, and the implications of the relationships described. The discussion highlights the complexity of interpreting relativistic concepts.

Who May Find This Useful

This discussion may be of interest to those studying relativistic physics, mathematical modeling in physics, or anyone exploring the nuances of mass and velocity relationships in the context of special relativity.

Uncle6
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The relativistic mass equation shows the relationship between relativistic mass and speed. Basically showing that the closer u get to light speed the less relativistic mass you have, but ur rest mass will be the same.

I was asked by my friend what the inverse of that formula means.

Thus I took the original equation and came up with the inverse: m = sqrt(c^2-(m0c^2/v)^2)

I also looked at the graph of the original and the inverse would just be a reflection about y=x.

I still can't interpret it. Any hints/ help?
 
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Uncle6 said:
The relativistic mass equation shows the relationship between relativistic mass and speed.

Do you mean

m = \frac{m_0}{\sqrt{1 - v^2 / c^2}}

Basically showing that the closer u get to light speed the less relativistic mass you have, but ur rest mass will be the same.

Don't you mean "more relativistic mass" (not "less")?

Thus I took the original equation and came up with the inverse: m = sqrt(c^2-(m0c^2/v)^2)

You must have made a mistake in your algebra somewhere. The units of the various quantities don't work out consistently in that equation. Also, if you started with the equation I gave above, an "inverse" equation would not start with "m =" but with "v =".
 
I switched m for v and isolated for m
 
We were supposed to guess that the relativistic mass in your equation was actually a velocity!? :confused: It's always a bad idea to change the meaning of the symbols without telling anyone.

If you solve the equation in jtbell's post for v, you get

v=c\sqrt{1-\frac{m_0^2}{m^2}}=c\sqrt{1-\frac{m_0^2c^4}{E^2}}

where E=mc2 is the energy. Note that v→c when E→∞.
 

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