My Math Forum  

Go Back   My Math Forum > Science Forums > Physics

Physics Physics Forum

Thanks Tree1Thanks
  • 1 Post By studiot
LinkBack Thread Tools Display Modes
April 2nd, 2017, 03:14 PM   #1
Joined: Aug 2015
From: USA

Posts: 10
Thanks: 0

HELP: Special Relativity Addition of Velocities Trigonometry

Hello guys, can anyone help me to understand how Einstein arrives at the equation for V? I do not understand or know how he introduces the trigonometry.

2nd equation.jpg3rd equation.jpg
Xaleb is offline  
April 3rd, 2017, 02:42 AM   #2
Senior Member
Joined: Jun 2015
From: England

Posts: 891
Thanks: 269

Elementary ttreatments of relativity present the motions in the Lorenz transformation as being parallel to one of the axis (usually the x axis).

Of course more generally the motion may not be parallel, in which case trigonometry becomes involved.

This is also true of the Galilean/Newtonian transformation.

I can't read your extracts properly but I think your velocity is in the xy plane ie normal to the z axis so only the angles in the original and transformed coordinate system are involved. Life is more complicated in true 3D where the velocity is not parallel to any axis.

Note that when you compare velocities in two coordinate systems you are effectively adding the relative velocity between the coordinate systems, that is where the (vector) addition comes in.

The use of the hyperbolic tangent function leads to a property known as the rapidity, which can be used to replace the ordinary velocity and leads to simpler equations.

If you would like to post proper readable sized images I can comment in more detail, appropriate to your presentation.
Thanks from topsquark

Last edited by studiot; April 3rd, 2017 at 03:21 AM.
studiot is offline  

  My Math Forum > Science Forums > Physics

addition, relativity, special, trigonometry, velocities

Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
Special Relativity SenatorArmstrong Physics 19 September 13th, 2016 02:50 PM
A question about velocity addition with relativity J Thomas Physics 5 January 18th, 2015 03:56 PM
Trigonometry addition formula problem adam848 Trigonometry 4 November 24th, 2014 01:07 AM
A challenge to the theory of special relativity Carl James Mesaros Physics 4 June 6th, 2014 01:32 PM
relative velocities mikeportnoy Algebra 1 February 18th, 2010 03:08 PM

Copyright © 2019 My Math Forum. All rights reserved.