document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=989333>Question 989333</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A body subject to air resistance is allowed to fall from the top of a 36 m tower. Given that the distance s metres, through which it falls in t seconds, is given by <BR>\n" );
document.write( "s = 5 t^2 &#8722; t^3 / 3,       0 &#8804; t &#8804; 3\r<BR>\n" );
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document.write( "what is the acceleration after 3 seconds, in m/s2. Please give an exact, possibly fractional, answer (no decimals).\r<BR>\n" );
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document.write( "Do I differentiate twice?<BR>\n" );
document.write( "So, (10t - 2t^2) / 3<BR>\n" );
document.write( "Then (10 - 4t) / 3\r<BR>\n" );
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document.write( "I'm stuck!\r<BR>\n" );
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document.write( "THANK YOU </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #609677 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=609677\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A body subject to air resistance is allowed to fall from the top of a 36 m tower. Given that the distance s metres, through which it falls in t seconds, is given by <BR>\n" );
document.write( "s = 5 t^2 - t^3 / 3,       0 < t < 3\r<BR>\n" );
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document.write( "what is the acceleration after 3 seconds, in m/s2. Please give an exact, possibly fractional, answer (no decimals).\r<BR>\n" );
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document.write( "Do I differentiate twice?<BR>\n" );
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document.write( "Acceleration is the 2nd derivative of displacement.<BR>\n" );
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document.write( "So, (10t - 2t^2) / 3  ***** = (10t - 3t^2)/3<BR>\n" );
document.write( "Then (10 - 4t) / 3 ***** = (10 - 6t)/3<BR>\n" );
document.write( "At t = 3: s\" = (10 - 18)/3 = -8/3<BR>\n" );
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document.write( "Seems odd that the acceleration is negative.<BR>\n" );
document.write( "--<BR>\n" );
document.write( "Maybe it's:<BR>\n" );
document.write( "s = 5t^2 - t^3/3<BR>\n" );
document.write( "s' = 10t - t^2<BR>\n" );
document.write( "s\" = 10 - 2t<BR>\n" );
document.write( "s\"(3) = 4 m/sec/sec<BR>\n" );
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document.write( "I have doubts about the given equation.<BR>\n" );
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