SOLUTION: the height in feet of a bottle rocket is given by h(t)=160t-t2 where t is the time in seconds. How long will it take for the rocket to return to the ground? thanks

Question 829633: the height in feet of a bottle rocket is given by h(t)=160t-t2 where t is the time in seconds. How long will it take for the rocket to return to the ground?
thanks

Found 3 solutions by Alan3354, lwsshak3, LinnW:
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
the height in feet of a bottle rocket is given by h(t)=160t-t2 where t is the time in seconds. How long will it take for the rocket to return to the ground?
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At impact, h(t) = 0
Solve for t. You get 2 values, 1 at launch, 1 at impact.
==============
PS That's the equation of a projectile.
Bottle rockets have thrust --> a 3rd order equation, not a quadratic.

Answer by lwsshak3(11628)   (Show Source): You can put this solution on YOUR website!
the height in feet of a bottle rocket is given by h(t)=160t-t2 where t is the time in seconds. How long will it take for the rocket to return to the ground?
***
When the rocket returns to the ground,its height=0
h(t)=160t-t2
0=160t-t2
-t^2+160t=0
-t(t-160)=0
t=0(reject,t>0)
or
t-160=0
t=160
How long will it take for the rocket to return to the ground? 160 seconds
Answer by LinnW(1048)   (Show Source): You can put this solution on YOUR website!

The rocket is on the ground when h(t) = 0
so solve

multiply by -1

factoring

So solutions for when the rocket is on the ground are 0 and 160
The rocket is back on the ground in 160 seconds.
Let me know if you need additional help.
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