Question

a ball is dropped from the top of a building of height 30 m then find the final velocity of the ball and time to reach the ground (a=10m/s)

Answer 1

s = u t + 1/2 g t^2
30 = 0 * t + 1/2* 10* t^2
t = sqrt 6 sec.

2as = v^2 - u^2
2*10*30 = v^2 - 0
v = 10* sqrt6 m/s

Answer 2

Initial vel. u = 0 m/s
Distance s= 30m
Acceleration a= 10 m/s2

Apply 2nd and 3rd equation of motion.