SOLUTION: If a stone is tossed from the top of a 230 meter building, the height of the stone as a function of time is given by h(t) = -9.8t^2 – 10t + 230, where t is in seconds, and height i

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: If a stone is tossed from the top of a 230 meter building, the height of the stone as a function of time is given by h(t) = -9.8t^2 – 10t + 230, where t is in seconds, and height i      Log On


   

Question 593595: If a stone is tossed from the top of a 230 meter building, the height of the stone as a function of time is given by h(t) = -9.8t^2 – 10t + 230, where t is in seconds, and height is in meters. After how many seconds will the stone hit the ground? Round to the nearest hundredth’s place; include units in your answer.
Found 2 solutions by ankor@dixie-net.com, Alan3354:
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
h(t) = -9.8t^2 – 10t + 230,
When it hits the ground, h(t) = 0, therefore
-9.8t^2 – 10t + 230 = 0
Use the quadratic formula to find t
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
In this problem: x=t; a=-9.8; b=-10; c=230
t+=+%28-%28-10%29+%2B-+sqrt%28-10%5E2-4%2A-9.8%2A230+%29%29%2F%282%2A-9.8%29+
:
t+=+%2810+%2B-+sqrt%28100%2B9016+%29%29%2F%28-19.6%29+
I'll let you do the rather tedious math here, you should get a positive solution of about 4.36 seconds

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
If a stone is tossed from the top of a 230 meter building, the height of the stone as a function of time is given by h(t) = -9.8t^2 – 10t + 230, where t is in seconds, and height is in meters. After how many seconds will the stone hit the ground? Round to the nearest hundredth’s place; include units in your answer.
--------------
The other tutor got the right answer, ~ 4.36 seconds, but
if you're on Earth, the equation is
h(t) = -4.9t^2 – 10t + 230