Disregarding air friction, the distance traveled by an object due to gravity is : H = 0.5*g*t^2. g is the gravitational constant at the surface of earth.
g= 9.81 m/s^2
After 3 seconds, Distance = .5*9.81*9 = 44.15 meters traveled.
Since it was dropped from a height of 90 meters, the current height is 90 - 44.15 = (a) 45.85 meters
(b) It has to travel 90 meters to hit the ground . So we must find t
Using the same equation
t = (2*H/g)^.5
t = (2*90/g)^.5 = 4.28 seconds until it hits the ground
