The velocity of a particle moving in the positive direction
of the x axis varies as v = al/x, where a is a positive constant.
Assuming that at the moment t = 0 the particle was located at the
point x = 0, find:
(a) the time dependence of the velocity and the acceleration of the
particle;
(b) the mean velocity of the particle averaged over the time that
the particle takes to cover the first s metres of the path.