
Archived: 07 Aug 2014, 10:07

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Roberto
Joined: 03 Jun 2010, 15:18 Posts: 136

Exercise [18.21]
Attached my solution.

29 Aug 2010, 14:05 


deant
Joined: 12 Jul 2010, 07:44 Posts: 154

Re: Exercise [18.21]
Actually Roberto, there's a very minor error in your posted solution:
dx/ds is not equal to v, it's proportional up to some scalar function of s, which depends on the choice of parameter s.
However, even with v = f(s) . dx/ds (where f(s) is a scalar), your first and third terms still cancel, since the f(s) appears in both  so nothing else in the solution is actually affected by this.

02 Jan 2012, 08:52 


Roberto
Joined: 03 Jun 2010, 15:18 Posts: 136

Re: Exercise [18.21]
Yes, of course you are right. In my calculations I made the standard choice for s: the affine parameter, i.e. the proper time. This makes v equal, instead that just proportional, to dx/ds. But I omitted to make explicit my choice; furthermore, this choice is not really necessary, as you pointed out: it is just a matter of convenience.

02 Jan 2012, 13:25 



