Quick check from College Physics, 28.4 Relativistic Addition of Velocities

Relativistic Addition of Velocities: quick check

Suppose a space probe moves away from the Earth at a speed $0.350 c$ . It sends a radio wave message back to the Earth at a frequency of 1.50 GHz. At what frequency is the message received on the Earth?

Answer it in your own words before you look.

Answer
$f_{obs} {=f}_{s} \sqrt{\frac{1 - \frac{u}{c}}{1 + \frac{u}{c}}} = (1 . 50 GHz) \sqrt{\frac{1 - \frac{0.350 c}{c}}{1 + \frac{0.350 c}{c}}} = 1 . 04 GHz$
28.39

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