Answer :
When the ball reaches the highest point, its velocity will be zero. So final velocity is :
v=0m/s
Here, the time to reach highest point is equal to time to hit ground from highest point.
Consider upward motion, the acceleration of the ball is
a=−g=−9.8m/s2
(minus for motion opposite to gravity)
If It be the required time.
Using
v=u+at,0=25+(−9.8)t⟹ t=2.5s
Thus the ball hits the ground after
2.5
seconds after reaching its highest point.
