Answer:
2.26 s
Explanation:
Let's take down to be positive.
Given (in the y direction):
Δy = 25 m
v₀ = 0 m/s
a = 9.8 m/s²
Find: t
Δy = v₀ t + ½ at²
25 m = (0 m/s) t + ½ (9.8 m/s²) t²
25 = 4.9t²
t = 2.26 s
If the ball instead had an initial horizontal velocity of 5 m/s, its initial vertical velocity is still 0 m/s. So the time to fall is still 2.26 s.
Answer:
Force on superball will be 
Explanation:
We have given mass of superball m = 52 gram = 0.052 kg
Velocity change from 20 m/sec downward to 14 m/sec upward
Let downward velocity is positive then upward velocity is negative
So downward velocity is + 20 m/sec and upward velocity is -14 m/sec
Time is given as 1800 sec
We know that acceleration is rate of change of velocity
So 
According to newton second law
Force = ma = 0.052×0.0188 
Circularity system........…….......
Now I can actually edit my answer directly: I'm fairly sure I've got this wrong, and my mind has gone blank for how to do it, if someone could delete this that would be great and I'll think about it and see if I can figure it out!