Solving for the Speed of a Star in a Binary System | Physics Wave Question

  • Thread starter Thread starter roxxyroxx
  • Start date Start date
  • Tags Tags
    Physics Wave
AI Thread Summary
To determine the speed of a star in a binary system relative to Earth, the Doppler effect is applied to the observed spectral line wavelength of 515.2 nm compared to the lab wavelength of 518.6 nm. The relevant formula involves the frequency shift, where the frequency of light changes due to the star's motion. By substituting the known values into the Doppler formula, the velocity of the star (Vs) can be calculated. A positive result indicates the star is moving away from Earth, while a negative result indicates it is approaching. This approach provides a classical understanding of the star's speed without needing to consider general relativity.
roxxyroxx
Messages
48
Reaction score
0

Homework Statement



a spectral line coming from a star in a binary system has a wavelength of 515.2 nm. in the lab the same spectral line would have a wavelength of 518.6 nm. what is the speed of the star in relation to earth?

Homework Equations


??


The Attempt at a Solution


??
 
Physics news on Phys.org
look up doppler effect, I'm not going to propose solution, because once you learn it for yourself -- I'm sure you'll figure it out in an instant (at least in a classical sense, not accounting the general relativity corrections -- there's not enough info in the problem to use that anyway).
 
Or you could try relativistic doppler effect.
 
Use the Dopple formula:

f'=f.V/(V+Vs)

V=c=3.10^8 m/s :speed of the radio wave.
Vs: velocity of the star (source).

U should find Vs, if it's positive then the star is moving away from the earth, otherwise it's moving closer.
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Speed of a star in Special Relativity
Replies
6
Views
1K
Properties of a Star Homework help
Replies
3
Views
2K
What is the observed wavelength of the Hα line?
Replies
3
Views
2K
Sun question: Determine the velocity of the gas
Replies
8
Views
2K
B Question: Orbital mechanics of a binary star system
Replies
5
Views
2K
Binary system of stars (##\alpha## - centauri)
Replies
5
Views
2K
Diffraction Grating Question, Dispersion and Resolving
Replies
2
Views
4K
Which Letter Represents a Star Similar to the Sun Based on Emission Spectra?
Replies
10
Views
2K
Using the Doppler formula to find radial speed of a star
Replies
1
Views
3K
Question about gravitational force(Binary star)
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top