SOLUTION: 5. A bottle rocket is fired from the ground upwards at 64 feet per second. a) What is the maximum height the bottle rocket reaches? b) How long does it take for the bottle rocket

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: 5. A bottle rocket is fired from the ground upwards at 64 feet per second. a) What is the maximum height the bottle rocket reaches? b) How long does it take for the bottle rocket       Log On


   

Question 879538: 5. A bottle rocket is fired from the ground upwards at 64 feet per second. a) What is the maximum height the bottle rocket reaches?
b) How long does it take for the bottle rocket to hit the ground?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+h%28t%29+=+-16t%5E2+%2B+64t+
When the form is
+ax%5E2+%2B+b%2Ax+%2B+c+, the vertex is
at +t%5Bmax%5D+=+-b%2F%282a%29+
+t%5Bmax%5D+=+-64%2F%28+2%2A%28-16%29%29+
+t%5Bmax%5D+=+2+
Now find +h%282%29+
+h%282%29+=+-16%2A2%5E2+%2B+64%2A2+
+h%282%29+=+64+
The max height is 64 ft
-----------------------
The rocket hits the ground when +h%28t%29+=+0+
+0+=+-16t%5E2+%2B+64t+
+0+=+t%2A%28+-16t+%2B+64+%29+
The rocket hits the ground when
+-16t+%2B+64+=+0+
+16t+=+64+
+t+=+4+
The rocket hits the ground in 4 sec
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Here's the plot:
+graph%28+400%2C+400%2C+-1%2C+6%2C+-5%2C+70%2C+-16x%5E2+%2B+64x+%29+