When will the sunglasses hit the ground?

Question

While hovering near the top of a waterfall in a national park at 6400 ​feet, a helicopter pilot accidentally drops his sunglasses. The height h(t) of the sunglasses after t seconds is given by the polynomial function h(t)=-16t²+6400.

Answer 1

set the height function = 0 and solve for t

-16t²+6400=0

t² = -6400/(-16)=400

t² = 400

t= the square root of 400 or 20

glasses hit the ground in 20 seconds