Recent content by Eivind

Well, the generators are those which are relatively prime to p^r.

Let p be a prime number. Find the number of generators of the cyclic group Z_(p^r), where r is an integer >=1. A small hint, please?

Well, I'm currently in my 11th year of school, and has two more years to go before starting at a university, so I'm expecting to start when I'm 18-19. In Norway there are 10 years of compulsory education, and then three years at an upper secondary school, if you want to. On the German students...

Yup, I think so.

Have anyone studied at Cambridge here? I'm planning to study mathematics there, and therefore I'd like to hear what students or former students of mathematics has to say about it. Positive and negatives, was it/is it challenging enough, environment, etc. I'm currently at my first year in upper...

You have the wavelenght, then you can calculate the frequency. After that you calculate the energy of the photons of each series. Then "translate" the energy into electron volts.

2e= 2*1.6e-19=3.2e-19 C 79e=79*1.6e-19=1.264e-17 C Just use Coulomb`s law.

Thank you for all the answers!

The answer was in the back of the book, and I got 4.2e30 kg, which, according to the book, is correct.

Thanks everyone, I got it right now! I should have realized there was no sentral object, thanks again!

Ok, Hootenanny, I`ll try that.

I have found the mass of the sentral object, but don't have a clue on the rest(correct answer:4.2e30 kg).

Oh, sorry . I`ll try to work it out.

d=vt d=80000 m/s*864000 s d=6.912e10 m d=2pi*r d/2pi=r r=6.912e10 m/2pi r=1.1e10 m yMm/r^2=m4pi^2r/t^2 M=4pi^2r^3/yt^2 M=(4pi^2*1.1e10m^3)/(6.67e-11*864000^2 s) M=1.05e30 kg g=yM/r^2 g=(6.67e-11*1.05e30 kg)/1.1e10^2 m g=0.58 N

Can anybody help me whit this? "Two stars which have the same mass are orbiting an object between the two stars. The velocity of the stars is 80 km/s and the time used on one orbit is 864000 s. Find the mass of the two stars." This is what I have done so far: r(radius)=1.1e10 m...