document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=813712>Question 813712</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A girl standing on the ground throws a tennis ball upwards into the air. The height in feet of the ball above the ground t seconds after being thrown is 80t-10t^2. The ball lands on a rood above her 6 seconds after being thrown.<BR>\n" );
document.write( "a) How high is the roof? (in feet)<BR>\n" );
document.write( "b) What is the velocity upwards of the ball after t seconds? (feet/sec)<BR>\n" );
document.write( "c) What was the speed of the ball when it hit the roof? (feet/sec)<BR>\n" );
document.write( "d) How high above the roof was the ball when the speed of the ball was zero? (feet) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #489912 by </B><A HREF=/tutors/aboutme.mpl?userid=richwmiller><B>richwmiller(17219)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=richwmiller><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=richwmiller><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=489912\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 80t-10t^2=0<BR>\n" );
document.write( "{t = 8)\r<BR>\n" );
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document.write( "a) 80t-10t^2 t=6 120 ft roof <BR>\n" );
document.write( "b)  -20 (t-4)<BR>\n" );
document.write( "c)64.3 ft per sec  or using the derivative 40<BR>\n" );
document.write( "c) see the table below<BR>\n" );
document.write( "d) max height was 160 at 4 seconds\r<BR>\n" );
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document.write( "Time <BR>\n" );
document.write( "(s)	Velocity	Distance<BR>\n" );
document.write( "         m/s	km/h	ft/s	mph	m	ft<BR>\n" );
document.write( "1	9.8	35.3	32.2	21.9	4.9	16.1<BR>\n" );
document.write( "2	19.6	70.6	[64.3]	43.8	19.6	64.3<BR>\n" );
document.write( "3	29.4	106	96.5	65.8	44.1	144.8<BR>\n" );
document.write( "4	39.2	141	128.7	87.7	78.5	257.4<BR>\n" );
document.write( "5	49.1	177	160.9	110	122.6	402.2<BR>\n" );
document.write( "6	58.9	212	193.0	132	176.6	579.1<BR>\n" );
document.write( "7	68.7	247	225.2	154	240.3	788.3<BR>\n" );
document.write( "8	78.5	283	257.4	176	313.9	1,029.6<BR>\n" );
document.write( "9	88.3	318	289.6	198	397.3	1,303.0<BR>\n" );
document.write( "10	98.1	353	321.7	219	490.5	1,608.7\r<BR>\n" );
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