document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=889062>Question 889062</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A projectile is launched from the ground with an initial velocity of V0 feet per second. Neglecting air resistance, its height in feet per seconds after launch is given by s = -16t^2 +V0t. Find the time(s) that the projectile will <BR>\n" );
document.write( "(a) reach a height of 240ft and <BR>\n" );
document.write( "(b) return to the ground when V0= 128 feet per second. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #538256 by </B><A HREF=/tutors/aboutme.mpl?userid=lwsshak3><B>lwsshak3(11628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=lwsshak3><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=538256\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A projectile is launched from the ground with an initial velocity of V0 feet per second. Neglecting air resistance, its height in feet per seconds after launch is given by s = -16t^2 +V0t. Find the time(s) that the projectile will <BR>\n" );
document.write( "(a) reach a height of 240ft and <BR>\n" );
document.write( "(b) return to the ground when V0= 128 feet per second.<BR>\n" );
document.write( "***<BR>\n" );
document.write( "set height,s=240<BR>\n" );
document.write( "(a) 240=-16t^2+128t<BR>\n" );
document.write( "-16t^2+128t-240=0<BR>\n" );
document.write( "-t^2+8t-15=0<BR>\n" );
document.write( "t^2-8t+15=0<BR>\n" );
document.write( "(t-5)(t-3)=0<BR>\n" );
document.write( "t=5<BR>\n" );
document.write( "or<BR>\n" );
document.write( "t=3<BR>\n" );
document.write( "projectile will reach a height of 240ft after 3 sec on the way up and after 5 sec on the way down<BR>\n" );
document.write( "..<BR>\n" );
document.write( "set height,s=0<BR>\n" );
document.write( "(b) -16t^2+128t=0<BR>\n" );
document.write( "-t^2+8t=0<BR>\n" );
document.write( "-t(t-8)=0<BR>\n" );
document.write( "t=0 (reject)<BR>\n" );
document.write( "or<BR>\n" );
document.write( "t=8<BR>\n" );
document.write( "projectile will  return to the ground after 8 sec<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );