A stone is dropped from the top of a tower. The height h in meters from where the stone is dropped to the ground is given by the function h = -5t^2+ 10t + 40, where t is the time in seconds. How long does it take for the stone to touch the ground?
F) 2 sec
G) 3 sec
H) 3.5 sec
J) 4 sec
pls i need help lol