$1.$A stone is projected upward with an initial velocity, $10$m$/$s$,$from the roof of a building. It takes $6$s to reach the ground. If g is $9\mathrm{.}81$m$/$s$2$and air resistance is neglected. Find :

a$)$the height of the building; and$($h $=116\mathrm{.}6$m$)$

b$)$the velocity of the stone when striking the ground.$($v $=-48\mathrm{.}86$m$/$s$)$