A projectile is launched from ground level with an initial velocity of vo feet per second. Neglecting air resistance, its height in feet t seconds after launch is given by s= - 16t² + vot. Find the time(s) that the projectile will (a) reach a height of 80 ft and (b) return to the ground when vo= 96 feet per second.
(a) Find the time(s) that the projectile will reach a height of 80 ft when Vo = 96 feet per second. Select the correct choice below and, if necessary, fill in the answer box to complete your choice.