SOLUTION: If an object is thrown upward with an initial veliocity of 64 ft/sec, its height after t sec is given by h = 64t - 16t^2. Find the numbrt of seconds the object is in the air begor

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: If an object is thrown upward with an initial veliocity of 64 ft/sec, its height after t sec is given by h = 64t - 16t^2. Find the numbrt of seconds the object is in the air begor      Log On


   

Question 137005: If an object is thrown upward with an initial veliocity of 64 ft/sec, its height after t sec is given by h = 64t - 16t^2. Find the numbrt of seconds the object is in the air begore it hits the ground.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
If an object is thrown upward with an initial velocity of 64 ft/sec, its height after t sec is given by h = 64t - 16t^2. Find the number of seconds the object is in the air before it hits the ground.
:
When the ball hits the ground, h = 0
-16t^2 + 64t = 0
Factor out -16t
-16t(t - 4) = 0
:
t = 0
and
t = 4 seconds for the object to hit the ground
:
:
Substitute 4 for t in the original equation to check it:
-16(4^2) + 64(4) =
-256 + 256 = 0