A rescue plane wants to drop supplies to isolated mountain climbers on a rocky ridge 235 m below. Assume the plane is traveling horizontally with a speed of 195 km/h (54.2 m/s).

Question

Suppose, instead, that the plane releases the supplies a horizontal distance of 425 m in advance of the mountain climbers. What vertical velocity (up or down) should the supplies be given so that they arrive precisely at the climbers' position (assume up is positive).
With what speed do the supplies land in the latter case?

Answer 1

425 = 54.2 t
t = 7.84 seconds in air

h = ho + Vi t - 4.9 t^2
-235 = Vi (7.84) - 4.9 (7.84)^2
-235 = 7.84 Vi - 301
Vi = 8.45 m/s up
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Horizontal speed = 54.2 always
find vertical speed at rocks
v = Vi - g t
v = 8.45 - 9.8 (7.84)
v = -68.4
so speed = sqrt (54.2^2 + 68.4^2)