document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=907494>Question 907494</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hello,<BR>\n" );
document.write( " It's been awhile since I asked this question. I have not gotten any response yet. <BR>\n" );
document.write( " If a paper plane is thrown from the top of an 147ft cliff into water,the height of the plane at any given time can be determined by h = -3t^2 + 147, where h is the height of plane at t seconds. After how many seconds will the plane be at height of 20.25ft?<BR>\n" );
document.write( "  I have  h = 3t^2 + 147<BR>\n" );
document.write( "          h(t) = 3^2 + 147 - 20.25ft<BR>\n" );
document.write( "          147 = 3t^2 = 6t = 147<BR>\n" );
document.write( "             0 = 3t^2 + 6t </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #550405 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=550405\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">   h = -3t^2 + 147<BR>\n" );
document.write( "-3t^2 is a very rough approximation of the acceleration due to gravity<BR>\n" );
document.write( "20.25ft = -3t^2 + 147 <BR>\n" );
document.write( "In each step that you took you changed an important element of the equation.\r<BR>\n" );
document.write( "\n" );
document.write( "h = 3t^2 + 147 here you changed gravity to a positive force making the paper plane rise and never fall<BR>\n" );
document.write( "h(t) = 3^2 + 147 - 20.25 ft here you left out the time <BR>\n" );
document.write( "h(t) is the height<BR>\n" );
document.write( "so plug in the 20.25 ft here<BR>\n" );
document.write( "20.25 = -3t^2 + 147<BR>\n" );
document.write( " -126.75= -3t^2<BR>\n" );
document.write( "42.25 =t^2<BR>\n" );
document.write( "6.5=t<BR>\n" );
document.write( "So after 6.5 second the plane is at 20.25 ft <BR>\n" );
document.write( "This is assuming that a breeze doesn't catch it and take it away </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );