Rearranging equation - Relativistic doppler

AI Thread Summary
To find the velocity of the hydra cluster, start by rearranging the relativistic Doppler equation. Divide both sides by 396.8 nm and square the result to isolate the term (1 + v/c)/(1 - v/c). Next, multiply both sides by (1 - v/c) and simplify the equation to gather all terms involving v on one side. Factor out v and divide by the coefficient to solve for v. This method effectively allows for the calculation of the cluster's velocity based on the observed spectral line shift.
roberto85
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Homework Statement


The hydra cluster is 900 Mpc (3x10^9 light years) away. Calcium atoms emit a spectral line of wavelength 396.8 nm. This line is observed at 487.5 nm. The velocity of the cluster, v, is given by (\lambda =c/f)

487.5 = 396.8 SQRT((1+v/c)/(1-v/c))

How do i find v please?


Homework Equations





The Attempt at a Solution

I need to rearrange and this example says take v/c to one side and solve but i don't know how. Well i have taken the numbers to one side, squared them and left with (1+v/c)/(1-v/c) on the other side, how do i find v? Thanks
 
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  1. Divide both sides by 396.8.
  2. Square both sides.
  3. Multiply both sides by (1 - v/c).
  4. Carry out the multiplication on the left side.
  5. Get all terms involving v on one side.
  6. Factor v out.
  7. Divide both sides by the coefficient of v.
That should pretty much do it
 
Thanks :)
 
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