A plane flying horizontally at a speed of 80 m/s at an elevation of 300 m drops a package of supplies. Five seconds later, the plane drops a second package. How far apart are the two packages after they hit the ground? (ignore air resistance and assume that the packages don't bounce, roll, or slide after hitting the ground)

400m

Distance apart = (80)(5) = 400m

Both packages would perform projectile motion when falling to the ground. Since horizontal displacement moved by both packages are the same, their difference would only be due to the additional distance travelled by the plane during the 5 second interval between dropping both packages.

need to see circuit to get time constant