Initial velocity of the ball (u) = 80 ft/ sec
Final velocity of the ball after reaching the ground (v) = 0
Distance covered by the ball to reach the ground (s) = 8 ft
Let "a" be the acceleration of the ball.
We know, [tex]2as=v^{2}-u^{2}[/tex]
[tex]2a(8)=0-80^{2}=-6400[/tex]
[tex]a=-\frac{6400}{16}[/tex]
[tex]a=-400ft/s^{2}[/tex]
Let "t" be the time required to reach the ground.
We know,
[tex]v=u+at[/tex]
[tex]t=\frac{v-u}{a}[/tex]
[tex]t=\frac{0-80}{-400}[/tex]
[tex]t=0.2s[/tex]
The ball will hit the ground in 0.2 second.
