First up, thin noncunducting ring with uniformly distributed charge Q on it, what's the potential a distance x from it, it's located on the axis of symmetry(ie on the axis passing through the center of the ring)(adsbygoogle = window.adsbygoogle || []).push({});

I really really really thought you could treat that ring as a point charge but apparently I'm wrrrrooooong

second, if you have a particle of mass m incident on nonmoving particle also of mass m with an initial momentum mc/2, what was its initial speed? I found that(after hours of forgetting the lorentz factor is (blah)^NEGATIVE1/2 oops)

after the collision you have two particles of mass m', one aimed 30 degrees above horizontal, one 30 degrees below...what's the momentum of each particle? hurrr? I tried to approach it the same way I did above(E^2=p^2c^2+mc^2 find E knowing p, E=gamma*mc^2, so for this problem I tried solving for p knowing E has to be the same as the previous, and it doesn't work. Primary problem is the answer doesn't involve m', hmm)

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# My topic full of GRE practice questions, whoo

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