Question 1185590
.
A flare is launched from a life raft {{{highlight(vertically_up)}}} {{{cross(an)}}} <U>at</U> initial velocity of 80 meters per second. 
How many seconds will it take the flare to fall back to the sea ?
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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;As it was written in the post, &nbsp;the condition was &nbsp;INCOMPLETE, &nbsp;since the direction of the launch was not specified.


&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;THEREFORE, &nbsp;I edited your post in order for the post would be meaningful.



<pre>
The function describing the height of this launched object (in meters over the sea level) versus time is


    h(t) = -5t^2 + 80t.


To find the time it takes the flare to fall back and to get the sea level is


    h(t) = 0,   or   -5t^2 + 80t = 0.


We factor it


     5t(16-t) = 0


and find two roots  t= 0  and  t= 16.


First root is not interesting for us (it describes the starting moment).


The other root, t= 16 seconds, is the solution to the problem.


<U>ANSWER</U>.  The flare will fall back to the sea in 16 seconds.
</pre>

Solved.


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&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Introductory-lesson-on-a-projectile-thrown-shot-launched-vertically-up.lesson>Introductory lesson on a projectile thrown-shot-launched vertically up</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-a-projectile-moving-vertically.lesson>Problem on a projectile moving vertically up and down</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-projectile-shooted-vertically-upward.lesson>Problem on an arrow shot vertically upward</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Typical-problems-on-an-projectile-moving-vertically-up-and-down.lesson>Problem on a ball thrown vertically up from the top of a tower</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-a-toy-rocket-launched-vertically-up--from-the-top-of-a-platform.lesson>Problem on a toy rocket launched vertically up from a tall platform</A>


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