$(6)$ Sidhu uses a $3\mathrm{.}64$ m long rope to pull Aarna $($m $=31\mathrm{.}8$ kg$)$ horizontally across the floor with a coefficient of kinetic friction of k$=0\mathrm{.}200$ at a constant speed of $5\mathrm{.}43$ m$/$s$.$ Aarna signals to Sidhu to stop by "plucking" the rope, sending a wave pulse forward along the rope. The pulse reaches Sidhu $327\mathrm{.}0$ ms later. What is the mass of the rope?$$