Question 65679
Find the time required for an object to fall to the ground from a building that is 1400ft high. 
displacement, y=1400
acceleration, a=32 ft/s^2 (This is the acceleration due to gravity)
initial velocity, v=0 because it is dropped
There are a couple of equations you can use, here's one:
{{{highlight(y=vt+(1/2)at^2)}}}
{{{1400=0t+(1/2)(32)t^2}}}
{{{1400=0+16t^2}}}
{{{1400=16t^2}}}
{{{1400/16=16t^2/16}}}
{{{1400/16=t^2}}}
{{{sqrt(1400/16)=t}}}  Ignore +\- because negative time has no meaning here.
{{{sqrt(100)*sqrt(14)/4=t}}}
{{{10*sqrt(14)/4=t}}}
{{{5*sqrt(14)/2=t}}}
t~~9.35414 s
If significant figures are important in your class, round off to 2 significant figures:
t~~9.4 s
Happy Calculating!!!