Question

Physicists tell us that altitude h in feet of a projectile t seconds after firing is h= -16t2 +vot +h0 where vo is the initial velocity in ft/s and ho is altitude in from which it is fired. If a rocket is launched from a hilltop 2400 ft above the desert with an initial upward velocity of 400 ft/s, then when will it land on the desert

Answer 1

is the answer 30seconds?