Answer:
a) 20 m/s
b) 5.83 seconds
c) 90.78 m
Explanation:
t = Time taken
u = Initial velocity = 20 m/s
v = Final velocity
s = Displacement
a = Acceleration due to gravity = 9.81 m/s²
a)

Time taken to reach maximum height is 1.22 seconds

So, the stone would travel 20.39 m up
s = 20.39 m

The ball is moving a 20 m/s at the time the ball passes the original height from which it was hit
b) Total height stone would fall is 20.39+50 = 70.39 m

Time taken by the ball to travel 70.39 m is 3.79 seconds
Total time taken by the ball to reach the ground from the time it left the person's hand is 2.04+3.79 = 5.83 seconds.
c) The ball travelled a distance of 20.39+50+20.39 = 90.78 m