SOLUTION: the height "h" of a rock, "t" seconds after it is dropped off a cliff is given by the equation: h=-16t(squared)+256. How many seconds after the rock is dropped will it hit the grou

Algebra ->  Equations -> SOLUTION: the height "h" of a rock, "t" seconds after it is dropped off a cliff is given by the equation: h=-16t(squared)+256. How many seconds after the rock is dropped will it hit the grou      Log On


   

Question 774213: the height "h" of a rock, "t" seconds after it is dropped off a cliff is given by the equation: h=-16t(squared)+256. How many seconds after the rock is dropped will it hit the ground?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+h+=+-16t%5E2+%2B+256+
You know it is being dropped from a cliff
that is +256+ ft high, because at
+t+=+0+, +h+=+256+
----------------------
The +-16t%5E2+ term tells you what
gravity is doing to the rock as the
seconds go by
----------------------
It will hit the ground when +h+=+0+, so
+0+=+-16t%5E2+%2B+256+
+16t%5E2+=+256+
+16t%5E2+=+16%5E2+
+t%5E2+=+16+
+t+=+4+
In 4 seconds the rock will hit the ground
Here's what the plot looks like:
+graph%28+400%2C+400%2C+-2%2C+6%2C+-30%2C+300%2C+-16x%5E2+%2B+256+%29+