Question

The height of a projectile is modeled by the function h(t) = −16t2 + v0t + h0 where t is the time in seconds that the projectile is in the air, v0 is the initial vertical velocity of the projectile, and h0 is the initial height of the projectile.


A football is kicked from ground level with an initial vertical velocity of 64 feet per second. After _____ seconds, the football will hit the ground.

Answer 1

as the football reaches ground it means that h(t) = 0 after t seconds

now as v0 = 64 feet per second
h0 = 0
thus we have
h(t) = −16t2 + v0t + h0
=> 0 = -16t2+64t + 0

now solve for t using quadratic formula

Answer 2

hmm idk how to do that

Answer 3

help me out

Answer 4

is it 3 s