SOLUTION: A firecracker shoots up from a hill 140 feet high with an initial speed of 100 feet per second. Using the formula {{{ H(t) = -16t^2 + vt + s }}}, approximately how long will

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: A firecracker shoots up from a hill 140 feet high with an initial speed of 100 feet per second. Using the formula {{{ H(t) = -16t^2 + vt + s }}}, approximately how long will       Log On


   

Question 611153: A firecracker shoots up from a hill 140 feet high with an initial speed of 100 feet per second. Using the
formula +H%28t%29+=+-16t%5E2+%2B+vt+%2B+s+, approximately how long will it take the firecracker to hit the ground?
Multiple choice : a) 5 seconds, b) 7seconds, c) 9 seconds, d) 11 seconds.
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
A firecracker shoots up from a hill 140 feet high with an initial speed of 100 feet per second. Using the
formula +H%28t%29+=+-16t%5E2+%2B+vt+%2B+s+, approximately how long will it take the firecracker to hit the ground?
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+H%28t%29+=+-16t%5E2+%2B+vt+%2B+s+
+H%28t%29+=+-16t%5E2+%2B+100t+%2B+140+
At impact, h(t) = 0
+H%28t%29+=+-16t%5E2+%2B+100t+%2B+140+=+0+
+-16t%5E2+%2B+100t+%2B+140+=+0+
Solve for t. Ignore the negative solution.