Answer:

Explanation:
If the stone will reach the top position of flag pole at t = 0.5 s and t = 4.1 s
so here the total time of the motion above the top point of pole is given as

now we have



so this is the speed at the top of flag pole
now we have



now the height of flag pole is given as



The initial velocity of the projectile is 19.8m/s
Explanation:
First, find time.
From our kinematics equations:
delta y = Vi•t + (1/2)at^2
rearrange,
t = sqrt[(2•delta y)/a]
t = sqrt[(2•20m)/9.8m/s^2]
t = 2.02s
Next, plug time into new kinematics equation to solve for the Vi in the x direction (horizontal)
delta x = Vi•t + (1/2)at^2
delta x = Vi•t
Rearrange:
Vi = delta x/t
Vi = 40m/2.02s
Vix = 19.8m/s
Then the magnitude of the net force is the difference between the two forces,
and its direction is the same as the direction of the greater one.
Acceleration = (16-25) / 2 = - 4.5 m/s^2