One end of a horizontal thick copper wire of length 2L and

One end of a horizontal thick copper wire of length 2L and radius 2R is welded to an end of another

        horizontal thin copper wire of length L and radius R. When the arrangement is stretched by applying forces       at two ends, the ratio of the elongation in the thin wire to that in the thick wire is?

The work done on a particle of mass m by a force K[x/(x^2+y^2)^3/2(i)  + y/(x^2+y^2)3/2(j)] (K being a constant of appropriate dimensions, when the particle is taken from the point (a, 0) to the point (0, a) along a circular path of radius a about the origin in the x-y plane is?