document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=222775>Question 222775</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The formula s=-16t^2 + vt + s gives you the height in feet above the earth at time t seconds for an object projected into the air with an initial velocity of v feet per second (ft/sec) from an initial height of s feet. Two balls are thrown into the sir simultaneously, one from the ground at 40 ft/sec and one from a height of 20 feet at 30 ft/sec. For what values of t will their heights above the ground differ by 10 feet or less?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #166719 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=166719\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The formula s=-16t^2 + vt + s gives you the height in feet above the earth at time t seconds for an object projected into the air with an initial velocity of v feet per second (ft/sec) from an initial height of s feet.<BR>\n" );
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document.write( "Two balls are thrown into the sir simultaneously, one from the ground at 40 ft/sec and one from a height of 20 feet at 30 ft/sec.<BR>\n" );
document.write( "1st ball: s(t) = -16t^2+40t+0<BR>\n" );
document.write( "2nd ball: s(t) = -16t^2+30t+20<BR>\n" );
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document.write( " For what values of t will their heights above the ground differ by 10 feet or less?<BR>\n" );
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document.write( "Equation:<BR>\n" );
document.write( "height - height <= 10 feet<BR>\n" );
document.write( "(-16t^2+30t+20) - (-16t^2+40t) <= 10 <BR>\n" );
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document.write( "-10t+20 <= 10<BR>\n" );
document.write( "-10t <= -10<BR>\n" );
document.write( "t >= 1 second (the heights will differ by at least 10 ft after the 1st second<BR>\n" );
document.write( "and until one of the balls reaches the ground.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.\r<BR>\n" );
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