an object falls directly from a plane flying horizontally at an altitude of 10000ft at 50mi/h. how long will it take to hit the ground?

Answer 1

It is a question which requires an unreasonable assumption, namely ignore air-resistance.

Without air-resistance, time it takes to reach ground is
t=sqrt(2H/g)
=sqrt(2*10000/32.2)
=24.9 s

The horizontal velocity of the plane does not change the time required.

If the dimensions and shape of the object is known, we can calculate the terminal velocity and the answer would be different.

Answer 2

t=sqrt(2H/g)
=sqrt(2*10000/32.2)
=24.9 s