Answer: 20.4 m
Explanation: speed v upward is v = vo -gt.
When maximum height v = 0, vo -gt = 0 and
T = vo / g = 20 m/s / 9.81 m/s² = 2.04 s
Now height y = vot -0.5 gt^2 = 20,4 m
This is possible to solve using
Conservation of energy Ek= Ep
0.5mv² = mgh. And h = v²/2g. Results same
