Posted by lisa on .
Can someone help me to understand how to work out this problem?
The pilot of an airplane traveling 240 km/h wants to drop supplies to flood victims isolated on a patch of land 160 m below. The supplies should be dropped how many seconds before the plane is directly overhead?

Physics 
bobpursley,
how long does it take an object to fall 160 m?

Physics 
lisa,
Bobpursley  I do not understand. The answer was 5.7 s and I have no idea what equation was used to get that.

Physics 
Matthew,
y = .5gt^2
160 = .5gt^2
= 5.71s