Question

The pilot of an airplane traveling 160 km/h wants to drop supplies to flood victims isolated on a patch of land 160m below. The supplies should be dropped how many seconds before the plane is directly overhead?

Answer 1

The horizontal speed of the supplies during the fall is the airplane speed (if you drop a bomb, then turn, because if you go straight it hits under you :)
so
how long to fall 160 meters?
(1/2) g t^2 = 60

t^2 = 120/g = 120/9.81
t = 3.5 seconds

Answer 2

isn't it
how long to fall 160 meters?
(1/2) g t^2 = 160 not


how long to fall 160 meters?
(1/2) g t^2 = 60

Answer 3

You're correct Lilly.
It's not a very good question anyway. It will fall in 5.7 seconds no matter how fast the thing is going. Who knows whether they get the supplies or not.