SOLUTION: can you please help me with this problem??? if an object is thrown vertically upward with an initial velocity v, from an original position of s, the height at any time is given

Click here to see ALL problems on Quadratic Equations

Question 763988: can you please help me with this problem???
if an object is thrown vertically upward with an initial velocity v, from an original position of s, the height at any time is given by: h= -16t^2+vt+s (where h and s are in ft, t is in seconds and v is in ft/sec)
if a rock is dropped from the top of a 200ft building, solve for the time that it takes for it to hit the ground (when h=0)
Hint: initial velocity when dropped is 0
Answer by rothauserc(4718) (Show Source):
You can put this solution on YOUR website!
we are given
h= -16t^2+vt+s (where h and s are in ft, t is in seconds and v is in ft/sec)
===============================================================================
the hint is v = 0 and h= 0 when the object hits the ground
0 = -16t^2 +0*t + 200
0 = -16t^2 + 200
divide both sides of = by -8
0 = 2t^2 -25
2t^2 = 25
t^2 = 25/2
t = 3.54 seconds