document.write( "Question 820472: A model rocket is launched (from the ground s0=0) with an initial velocity (V0) of 320 ft./sec.
\n" ); document.write( "a. Find the Position equation for the rocket
\n" ); document.write( "b. How high did the rocket get? (find the y coordinate of the vertex)
\n" ); document.write( "c. How long did the rocket take to reach its maximum height? (find the x coordinate of the vertex)
\n" ); document.write( "d. How long did the rocket take to return to earth?
\n" ); document.write( "e. How fast was the rocket going when it hit the ground?\r
\n" ); document.write( "\n" ); document.write( "I am very lost on this
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Algebra.Com's Answer #493595 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
(a)
\n" ); document.write( "The equation is:
\n" ); document.write( "\"+y%28x%29+=+-16x%5E2+%2B+320x+\"
\n" ); document.write( "This is a parabola with a maximum that
\n" ); document.write( "begins at ( x,y ) = ( 0,0 )
\n" ); document.write( "The squared term is entirely the
\n" ); document.write( "effect of gravity pulling the rocket down
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\n" ); document.write( "(b)
\n" ); document.write( "The x-coordinate of the vertex is at
\n" ); document.write( "\"+-b%2F%282a%29+\"
\n" ); document.write( "\"+a+=+-16+\"
\n" ); document.write( "\"+b+=+320+\"
\n" ); document.write( "------------
\n" ); document.write( "\"+-b%2F%282a%29+=+-320+%2F+%28+2%2A%28-16%29+%29+\"
\n" ); document.write( "\"+-b%2F%282a%29+=+-320%2F%28-32%29+\"
\n" ); document.write( "\"+-b%2F%282a%29+=+10+\"
\n" ); document.write( "------------------
\n" ); document.write( "To find the y-coordinate of the vertex, plug
\n" ); document.write( "this value of \"+x+\" back into the equation
\n" ); document.write( "\"+y%28x%29+=+-16x%5E2+%2B+320x+\"
\n" ); document.write( "\"+y%2810%29+=+-16%2A%2810%29%5E2+%2B+320%2A%2810%29+\"
\n" ); document.write( "\"+y%2810%29+=+-1600+%2B+3200+\"
\n" ); document.write( "\"+y%2810%29+=+1600+\"
\n" ); document.write( "The maximum height is 1600 ft
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\n" ); document.write( "(c)
\n" ); document.write( "The rocket took 10 sec to reach the maximum height
\n" ); document.write( "----------------------
\n" ); document.write( "(d)
\n" ); document.write( "You have to find out when the height, \"+y%28x%29+\",
\n" ); document.write( "is zero again, so you have to find both roots
\n" ); document.write( "\"+y%28x%29+=+-16x%5E2+%2B+320x+\"
\n" ); document.write( "\"++-16x%5E2+%2B+320x+=+0+\"
\n" ); document.write( "\"+x%2A%28+-16x+%2B+320+%29+=+0+\"
\n" ); document.write( "\"+-16x+%2B+320+=+0+\"
\n" ); document.write( "\"+16x+=+320+\"
\n" ); document.write( "\"+x+=+20+\"
\n" ); document.write( "The rocket took 20 sec to come back to earth
\n" ); document.write( "------------------
\n" ); document.write( "(e)
\n" ); document.write( "The velocity when it hit the ground is the same as it
\n" ); document.write( "was at takeoff, 320 ft/sec
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\n" ); document.write( "Here's a plot of the equation:
\n" ); document.write( "\"+graph%28+400%2C+400%2C+-4%2C+25%2C+-200%2C+2000%2C+-16x%5E2+%2B+320x+%29+\"\r
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