Answer:
(a) 24.87 GHz (b) 3.55 GHz
Explanation:
We have given the speed of the spaceship =0.75 c, here c is the speed of the light
(a) In the first case the ship is moving towards the alpha century
So the frequency is given by [tex]f'=f\times \sqrt{\frac{c+0.75c}{c-0.75c}}=9.4\times \sqrt{\frac{c+0.75c}{c-0.75c}}=24.87GHz[/tex]
(b) In this case the ship is moving away from the alpha century
So frequency is given by [tex]f'=f\times \sqrt{\frac{c-0.75c}{c+0.75c}}=9.4\times \sqrt{\frac{c-0.75c}{c+0.75c}}=3.55GHz[/tex]