Question

mary pitches a ball. the initial height is 8 ft and velocity 80 ft per second. when will the ball hit the ground?

Answer 1

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,
`2as=v^(2)-u^(2)`

`2a(8)=0-80^(2)=-6400`

`a=-(6400)/(16)`

`a=-400ft/s^(2)`

Let "t" be the time required to reach the ground.

We know,

`v=u+at`

`t=(v-u)/(a)`

`t=(0-80)/(-400)`

`t=0.2s`

The ball will hit the ground in 0.2 second.