Stuck on simple algebra problem

ck99

Hi folks, I am working through a section on the classical limit of the relativistic doppler shift, but I am stuck on some algebra, I think it should be really basic but I just can't get it to work! My notes go from

w = w'(1 - B)

to

(w' - w)/w = B

The context doesn't matter here really, I am just trying to work out the algebraic steps to go from

y = x(1 - B)

to

( x - y) / y = B

I have spent over an hour going around in circles and it seems impossible, have I copied something down wrong or can it be done?

FalseVaccum89

I'm almost certain your derivation is completely messed up. It would help if you posted an example of your logical progression from the first to the second equation.

For instance, the primed W is a multiplied variable on the RHS, but a subtracted one on the LHS. Then you've got the constant "1" that magically disappears. . . :what:

Norwegian

Quote by ck99

My notes go from

w = w'(1 - B)
to
(w' - w)/w = B

This becomes correct if you replace the last w with w'

ck99

That's what I did first of all, but the classical doppler shift equation is Δw/w = B and not Δw/w' = B.

The starting point comes from the Lorentz transform between frames of a photon emitted parallel to the particles motion, in the non-relativistic limit (ie using a Mclaurin series to get the (1-B) factor where B = v/c).

Similar Threads for: Stuck on simple algebra problem
Thread	Forum	Replies
Stuck on Algebra in Time Dilation Problem.	Introductory Physics Homework	2
Stuck on this simple physics problem.	Introductory Physics Homework	3
should be a simple problem... but im stuck	Introductory Physics Homework	1
Stuck on this Algebra Problem	Introductory Physics Homework	3
Gravitation Problem (stuck on Algebra!!)	Introductory Physics Homework	1

FalseVaccum89 Recognitions: Gold Member	I'm almost certain your derivation is completely messed up. It would help if you posted an example of your logical progression from the first to the second equation. For instance, the primed W is a multiplied variable on the RHS, but a subtracted one on the LHS. Then you've got the constant "1" that magically disappears. . . :what:

ck99	Stuck on simple algebra problem That's what I did first of all, but the classical doppler shift equation is Δw/w = B and not Δw/w' = B. The starting point comes from the Lorentz transform between frames of a photon emitted parallel to the particles motion, in the non-relativistic limit (ie using a Mclaurin series to get the (1-B) factor where B = v/c).