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

AI Thread Summary
The discussion focuses on understanding the equations related to relativistic mass, length contraction, and time dilation. Length contraction is expressed as v = c √{1-(l'/lo)^2}, while the time dilation equation remains unspecified. The concept of "relativistic mass" is deemed outdated and potentially confusing, with a recommendation to refer to more modern interpretations of mass in relativity. Participants emphasize the importance of grasping the application of these equations rather than just memorizing them. Overall, the conversation highlights the need for clarity in teaching and understanding relativistic concepts in physics.
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OK you need to do relativistic mass for passing exams - just understand that it is an out of date concept.
 
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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:
 
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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OK you need to do relativistic mass for passing exams - just understand that it is an out of date concept.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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