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Doppler shift watch

1. Hi
I am glad that my exams are over for now, lol time to rejoice for a bit. Anyways, i am pretty confident with my ph4 physics paper today,Although there are few questions i am doubtful of.Those are:
1)First was based on the Doppler shift.A graph of radial velocity(1650m/s) against time period was given, and the observed wavelength was 660nm.
By using Doppler shift formula the answer i got was 0.12nm.i.e
Change in lambda/ actual lambda = v/c? Is this correct?

The other one was about finding out the mass of the star (now i don't remember if it was a brown dwarf star or just a star).Given stars mass was about 8x10^30 , it was also said in the question that the mass which you are going to find is considerably less than 8x10^30. So after manipulating
t=2(pie)cube root d^3/G(m1+m2) i got answer of (not quite sure about it)
7x10^15 kg .(but it was definitely something to the power 15 lol). Can someone kindly let me know if i am even near to their solution or on the right track.Thanks
2. Anyone ?
3. yeah z = v/c which is Hod/c
4. I dont remember Whats the second question Whats that exercise ? Number ?
oh whats ur board ?
200th post ! Hurrey !
5. (Original post by Neofytos)
I dont remember Whats the second question Whats that exercise ? Number ?
oh whats ur board ?
200th post ! Hurrey !
Congrats on your 200th post, its WJEC .
6. (Original post by boromir9111)
yeah z = v/c which is Hod/c
Thanks for your reply , ah so you mean z (redshift) = v/c , so yea from what it looks like i think its pretty correct, nothing to worry about.
As for the second question ermm... yea since i cant recall much info its pretty much pointless , i hope i did it the right way though .Thanks for your reply.

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