Question

A ball is dropped from a tower 500m high, after how much time does it strike the ground??

Answer 1

Author has 765 ... the velocity after a 10.1 second drop is just a*t = 98.98 .... It hits the ground with a velocity of ...

Answer 2

let the acceleration due to gravity = 10 m/s^2 
now s = ut + 1/2at^2 
500 = 0 + 1/2(10)t^2
500 = 5t^2 
t^2 = 100 
t = 10 seconds