Question 86686
Well, you are given the formula for finding the time for the object to fall a distance of s feet.
You are also given the distance, s, which is just the height of the building from which the object is dropped.
So all you really need to do is to substitute the given value of s (1400 feet)into the appropriate place in the formula and evaluate it.
{{{t = (1/4)sqrt(s)}}} Substitute s = 1400.
{{{t = (1/4)sqrt(1400)}}} Simplify.
{{{t = (1/4)*10*sqrt(14)}}}
{{{t = 2.5sqrt(14)}}}seconds.  This is the exact answer.
{{{t = 2.5(3.74)}}}
{{{t = 9.35}}}seconds, approximately.