When mass M is at the position , it is sliding down the inclined part of a slide at a speed of $2\mathrm{.}15$ m$/$s$.$ The mass stops a distance S$2=1\mathrm{.}9$ m along the level part of the slide. The distance S$1=1\mathrm{.}23$ m and the angle $=29\mathrm{.}30.$ Calculate the coefficient of kinetic friction for the mass on the surface.