# The star Sirius is moving toward us?

at 7600

m/s. A line in its spectrum has a frequency o

5.71x1014 Hz when stationary. How much

will the frequency of the line be shifted?

### 1 Answer

Relevance

- NCSLv 71 year agoFavorite Answer
For a stationary receiver (observer),

new frequency f = F₀*c/(c + v) ← v -ve if src moving toward rcvr

using c = 299 792 458 m/s,

new f = 5.71e14Hz * 299792458m/s / (299792458m/s - 7600m/s)

new f = 5.7101447571444719199259890571258e+14 Hz

and so the shift is

Δf = f - F₀ = 1.447571444719199259890571257605e+10 Hz ≈ 1.45e10 Hz

Hope this helps!

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