document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=724176>Question 724176</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A ball is thrown upward from the top of a 240 foot building. The ball is 256 feet above ground level a fter 1 second, and it reaches ground level in 5 seconds.  the height above ground is a quadratic function of the time after the ball is thrown.  Write the equation of this function.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #443634 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=443634\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A ball is thrown upward from the top of a 240 foot building. The ball is 256 feet above ground level a fter 1 second, and it reaches ground level in 5 seconds.  the height above ground is a quadratic function of the time after the ball is thrown.  Write the equation of this function. <BR>\n" );
document.write( "------------<BR>\n" );
document.write( "It's the common formula for projectiles on Earth.<BR>\n" );
document.write( "h(t) = -16t^2 + vt + h, h in feet<BR>\n" );
document.write( "------<BR>\n" );
document.write( "h(1) = -16 + v + 240 = 256<BR>\n" );
document.write( "v = 32 ft/sec (the upward speed at launch)<BR>\n" );
document.write( "----<BR>\n" );
document.write( "h(t) = -16t^2 + 32t + 240 is the equation<BR>\n" );
document.write( "----<BR>\n" );
document.write( "h(5) = -400 + 160 + 240 = 0 confirms impact at t = 5 seconds<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );