- #1

criznet

## Main Question or Discussion Point

i've been having a tough time trying to solve the following problem.

A pulsating star has a period of 3 sec as seen from the rest mass frame of the star. What is the period of the star as measured by an observer traveling 2.2e8 m/s with respect to the star?

I assumed that it was simply the doppler shift for light and I found the equation.

f` = f sqrt(1+v^2/c^2) / sqrt(1 - v^2/c^2).

So in changed the given period of 3 sec to frequency by inverting it. plugged in 2.2e8 for v and 3.0e8 for c. I came up with the observed frequency and inverted it for my answer, but it seems that i am incorrect. anyone have insight into this?

dave

A pulsating star has a period of 3 sec as seen from the rest mass frame of the star. What is the period of the star as measured by an observer traveling 2.2e8 m/s with respect to the star?

I assumed that it was simply the doppler shift for light and I found the equation.

f` = f sqrt(1+v^2/c^2) / sqrt(1 - v^2/c^2).

So in changed the given period of 3 sec to frequency by inverting it. plugged in 2.2e8 for v and 3.0e8 for c. I came up with the observed frequency and inverted it for my answer, but it seems that i am incorrect. anyone have insight into this?

dave