The height h, in feet, of a projectile t seconds after launch is modeled by the equation h = 32t – 16t2. how long after launch does the projectile return to the ground? 2 seconds4 seconds14 seconds16 seconds

dy/dx h = 32t - 16t^2
v = 32 - 32t
at Max hight speed is 0m/s
therefore

0 = 32 - 32t
t = 32/32 = 1 s

so it goes up to Max hieght in 1 s
and it takes another 1s to come back
thus time after launch to return to ground is 2s!