Question

if the ball thrown up from the ground reaches to the maximum height of 20m.
(a) find its initial velocity
(b)the time taken to reach the highest point the
(c)velocity just before hitting the ground

Answer 1

h = u2 / 2g
u = 20 m / s
time of ascent =
$\sqrt{2h \div g$

time = 2 sec
velocity on reaching the ground = 20 m/ sec