document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=386394>Question 386394</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An object is thrown downward from a plane which is 380 m above the ground. The object is thrown with an initial velocity of 20 m/sec. How long does it take to reach the ground? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #273139 by </B><A HREF=/tutors/aboutme.mpl?userid=richard1234><B>richard1234(7193)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=richard1234><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=richard1234><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=273139\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> We must first choose a frame of reference. Here, I let the acceleration due to gravity be negative, and the ground is at 0 meters.\r<BR>\n" );
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document.write( "Now we have <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0+=+%281%2F2%29%28-9.8t%5E2%29+-+20t+%2B+380 ALIGN=MIDDLE  ALT=\"0+=+%281%2F2%29%28-9.8t%5E2%29+-+20t+%2B+380\"   DISABLED_style= \"max-width:90%; height:auto;\" > (Note that all units must be consistent, so I ignored them for now)\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0+=+-4.9t%5E2+-+20t+%2B+380 ALIGN=MIDDLE  ALT=\"0+=+-4.9t%5E2+-+20t+%2B+380\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "Now, just solve using the quadratic formula:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t+=+%2820+%2B-+sqrt%287848%29%29%2F%28-9.8%29 ALIGN=MIDDLE  ALT=\"t+=+%2820+%2B-+sqrt%287848%29%29%2F%28-9.8%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 6.99887...seconds (quite close to 7 s) </SPAN>\n" );
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