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nick227
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Homework Statement
A spaceship moves radially away from the Earth with an acceleration of 20m/c2. How long does it take the sodium street lamps ([tex]\lambda[/tex]=589 nm) on Earth to be invisible (with a powerful telescope) to the human eye of the astronauts? The visible spectrum is 400-700nm.
Homework Equations
fobs = ((1+(v/c))1/2/(1-(v/c))1/2) fsource
The Attempt at a Solution
I can use the doppler shift equation, to solve for velocity, but what should I use for fobs? Should I use 400nm or 700nm. I'm thinking 400 nm because of length contraction...
After I find a velocity, I can use the acceleration given and solve for time.