document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=78382>Question 78382</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The only part of the height equation we have not discussed is the constant. You have probably noticed that the constant is always equal to the initial height of the ball (80 m in our previous exercises.) Now let’s have you develop a height equation. A ball is thrown upward from the roof of a building 100 m tall with an initial velocity of 20m/s. <BR>\n" );
document.write( "h = -5t^2 + 20t +100<BR>\n" );
document.write( "37. Science and medicine. How long does it take the ball to fall back to the ground?<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #56201 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=56201\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> h = -5t^2 + 20t +100<BR>\n" );
document.write( "37. Science and medicine. How long does it take the ball to fall back to the ground?\r<BR>\n" );
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document.write( "The height is zero when the ball is back on the ground.<BR>\n" );
document.write( "Solve -5t^2+20t+100=0<BR>\n" );
document.write( "t^2-4t-20=0<BR>\n" );
document.write( "t=[4+-sqrt(16-4*-20)]/2<BR>\n" );
document.write( "t=[4+-sqrt(96)]/2<BR>\n" );
document.write( "t=[4+-4sqrt6)[/2<BR>\n" );
document.write( "t=[2+-2sqrt6]<BR>\n" );
document.write( "The positive answer is:<BR>\n" );
document.write( "t=2+2sqrt6 = 6.9 seconds<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28400%2C300%2C0%2C10%2C-2%2C150%2C-3x%5E2%2B20x%2B100%29 ALIGN=MIDDLE  ALT=\"graph%28400%2C300%2C0%2C10%2C-2%2C150%2C-3x%5E2%2B20x%2B100%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "===============<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H,<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );