A cargo helicopter, descending steadily at a speed of 4.1 m/s, releases a small package. Let upward be the positive direction for this problem.
(a) If the package is 92 m above the ground when it is dropped, how long does it take for the package to reach the ground?
v = Vi - 9.81 t
h = Hi + Vi t - 4.9 t^2
so
v = -4.1 - 9.81 t
h = 92 - 4.1 t - 4.9 t^2
at ground h = 0
-4.9 t^2 -4.1 t + 92 = 0
t = -4.77 or +3.93
v must be - on the way down so +3.93 seconds