document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=146488>Question 146488</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A ball is thrown  vertically upward from the ground with an initial speed of 80 ft/sec. Its height is given by h=80t-16t^2. How high does the ball go? When does the ball hit the ground? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #106965 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=106965\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A ball is thrown  vertically upward from the ground with an initial speed of 80 ft/sec. Its height is given by h=80t-16t^2. How high does the ball go? When does the ball hit the ground?<BR>\n" );
document.write( "--------------<BR>\n" );
document.write( "h(t) = 80t-16t^2<BR>\n" );
document.write( "------<BR>\n" );
document.write( "maximum height occurs when t = -b/2a = -80/(2*-16) = 5/2 = 2.5 seconds<BR>\n" );
document.write( "------<BR>\n" );
document.write( "The height when t=2.5 sec is t(2.5) = 80*2.5 - 16*(2.5)^2 = 100 ft.<BR>\n" );
document.write( "--------<BR>\n" );
document.write( "The ball hits the ground when the h(t) = 0<BR>\n" );
document.write( "80t - 16t^2 = 0<BR>\n" );
document.write( "16t(5-t) = 0<BR>\n" );
document.write( "t= 0 (it starts on the ground)<BR>\n" );
document.write( "or <BR>\n" );
document.write( "t= 5 seconds (it is back on the ground in 5 seconds)<BR>\n" );
document.write( "=============<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );