A ball tossed upward reaches a maximum height of 3.0m. Show that its initial speed was 7.7m/s.

Vf^2 = Vo^2 + 2gd = 0,

Vo^2 + 2 * (-9.8) * 3 = 0,
Vo^2 - 58.8 = 0,
Vo^2 = 58.8,
Vo = 7.7m/s.