V=? for Relativistic Mass,length contraction & time dilation

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Homework Help Overview

The discussion revolves around understanding velocity equations related to relativistic mass, length contraction, and time dilation. Participants are exploring these concepts for future reference rather than for immediate homework assistance.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the derivation of the length contraction equation and question how similar reasoning could be applied to time dilation. There is also a debate regarding the relevance of the concept of relativistic mass, with some participants suggesting it is outdated.

Discussion Status

The conversation is ongoing, with participants sharing insights and clarifying their understanding of the equations. Some guidance has been offered regarding the interpretation of relativistic mass and its historical context, but no consensus has been reached on the necessity of this concept in current physics.

Contextual Notes

There are mentions of confusion arising from different forms of equations encountered in lessons and online resources. Participants are also navigating the implications of educational practices regarding the teaching of relativistic mass.

Axidecimal
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Homework Statement


Velocity Equations for Relativistic Mass,length contraction and time dilation.
I was able to figure out one. This is not for homework. I want to learn these equations for future reference.

Homework Equations


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The Attempt at a Solution



Length Contraction : v = c √{1-(l'/lo)^2}
Time Dilation: ?
Mass: ?
 
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Just so I understand how you are thinking so I can answer properly:
How did you work out the length-contraction equation? Why not do the same thing for time dilation?

Note: no such thing as "relativistic mass". Used to be a thing but it turns out not to be much of a useful concept.
 
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l'/lo = √{1-v^2/c^2}
(l'/lo)^2 = 1-v^2/c^2
1-(l'/lo)^2 = v^2/c^2
√{1-(l'/lo)^2} = v/c
c√{1-(l'/lo)^2} = v

Mass increase has not been discontinued in my program.
 
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Why not do the same thing for time dilation?

OK you need to do relativistic mass for passing exams - just understand that it is an out of date concept.
 
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1481091214815-575886308.jpg

I just copied the equations from wiki to this platform but i now have come to realize they are the same.
This is pretty self explanatory. i was given equations from my lessons that were essentially the same but all look different so i got confused. I didnt even look at the wiki equations closely until now :sorry:o_O:frown:
 
Last edited:
Simon Bridge said:
OK you need to do relativistic mass for passing exams - just understand that it is an out of date concept.
Better still: Point your teachers to my Insight post What is relativistic mass and why it is not used much? or refer them to me. It is simply a concept that is not used in physics today and it is really just confusing people to use it. Unfortunately, the concept permeates much of the introductory physics literature - which often is not written by people with specialist knowledge on relativity - and therefore becomes used by teachers at pre-university and introductory university level.
 
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Axidecimal said:
View attachment 110045
I just copied the equations from wiki to this platform but i now have come to realize they are the same.
This is pretty self explanatory. i was given equations from my lessons that were essentially the same but all look different so i got confused. I didnt even look at the wiki equations closely until now :sorry:o_O:frown:
Well done.
The form of the equations is ##x = \frac{y}{\sqrt{1-z^2}}## and you want to solve for ##z##.
It does not matter what the actual letters are.

It is more important to understand how to use the equations - that is the hard part to get your head around.
 

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