A) Starting from rest, we have the entire cycle determined by 0.8s.
If we assume a constant movement, half of that time is when it reaches the highest point, that is, in 0.4s.
The distance as a function of speed and acceleration is given by,
[tex]d=v_it+\frac{1}{2}at^2[/tex]
At the initial point the speed is zero and the acceleration is equivalent to gravity.
[tex]d= 0+ \frac{1}{2}9.8*0.4^2[/tex]
[tex]d=0.784m[/tex]
B) When returning to the ground, the final speed is zero. Therefore, the equation that relates velocity to acceleration is given by,
[tex]V_f = V_i+at[/tex]
[tex]0 = V_i -9.8(0.4)[/tex]
[tex]V_i = 3.92m/s[/tex]