From the equation of motion, we know,
Where s= displacement
u= initial velocity
a= gravitational force
t= time
Displacement is 0 since the ball comes back to the same point from where it was thrown.
A = since the ball is thrown upwards.
Plug the known values into the equation.
=>
Solving for u gives :
u= 16.67 m/ sec ....... equation (1)
At maximum height, final velocity i.e v is 0
Time take to reach the top =
=>
Solving for s we get
s= 14.16 m