a boy throw a ball upward from the top of a cliff 73m high. Calculate the time in which ball will fall on the ground and the velocity of ball at that time

The ball rises for v/g seconds; which equals 14.7/9.8=1.5 seconds. After this time, it's height will be:

h (t) = g/2 (1.5) ²+14.7 (1.5)

=-4.9 x 2.25 + 22.05

=11.025m

The ball then falls for 49+11.025=60.025m, which takes:

g/2t²=60.025

t²=12.25

t=3.5 secs

Total time: 1.5+3.5=5 seconds