$8.$ OK$,$ same sort of track, but now with d $=3\mathrm{.}68$ m$.$ Now suppose the blocks starts on the track at x $=3\mathrm{.}31$ m$.$ The block is given a push to the left and begins to slide up the track, eventually reaching its maximum height at x $=0,$ at which point it turns around and begins sliding down. What was its initial speed in this case?a$\mathrm{.}7\mathrm{.}43$ m$/$sb$.7\mathrm{.}64$ m$/$sc$\mathrm{.}5\mathrm{.}40$ m$/$sd$\mathrm{.}5\mathrm{.}22$ m$/$s