This is the boss. No calculator — today $g = 10\ \mathrm{m/s^2}$, stated on the paper, and every draw is chosen to fit in your head. One flare, one long problem, and every answer feeds the next: the moment of the peak (that is the VERTEX of $h(t) = -5t^2 + v_0 t + h_0$, where $v_0$ — v-nought — is the launch speed in m/s and $h_0$ the platform height in metres), then the height it buys, then the discriminant of the landing equation, then the landing itself (that is a ROOT). Write each line down: one early slip rides the parabola all the way into the water.

Two things to hold onto. Here $a = -5$, which is NEGATIVE — so the minus branch of the quadratic formula is the one that lands in the future, and the plus branch returns a phantom time from before the launch. And because the flare starts on a platform rather than at the water, the flight is NOT symmetric: it falls further than it climbed, so the landing time is more than twice the peak time. Everything in the chapter plays here. 5★ under par is the chapter crown.