SOLUTION: The height of an object thrown upward from the floor of a canyon 106 ft. deep, with an initial velocity of 120 ft/sec is given by the equation: h=-16t2 + 120t-106 How long will i

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: The height of an object thrown upward from the floor of a canyon 106 ft. deep, with an initial velocity of 120 ft/sec is given by the equation: h=-16t2 + 120t-106 How long will i      Log On


   

Question 466060: The height of an object thrown upward from the floor of a canyon 106 ft. deep, with an initial velocity of 120 ft/sec is given by the equation:
h=-16t2 + 120t-106 How long will it take the object to rise to the height of the canyon wall? Round answer to the nearest hundreth.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The height of an object thrown upward from the floor of a canyon 106 ft. deep,
with an initial velocity of 120 ft/sec is given by the equation:
h=-16t2 + 120t-106 How long will it take the object to rise to the height of the canyon wall?
Round answer to the nearest hundreth.
:
Height of the canyon wall = 0, depth of the canyon -106, so we have
-16t^2 + 120t - 106 = 0
Use the quadratic formula:
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
In this equation: t=x, a=-16, b-120, c=-106
t+=+%28-120+%2B-+sqrt%28120%5E2-4%2A-16%2A-106+%29%29%2F%282%2A-16%29+
:
t+=+%28-120+%2B-+sqrt%2814400-6784+%29%29%2F%28-32%29+
:
t+=+%28-120+%2B-+sqrt%287616+%29%29%2F%28-32%29+
Two solutions
t+=+%28-120+%2B+87.27%29%2F%28-32%29+
t = %28-32.73%29%2F%28-32%29
t = 1.023 sec, this is the solution we want, time at the top of the wall on the way up