document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=967192>Question 967192</A>: <I><SPAN STYLE=\"word-break: break-all;\"> To stop a moving car takes some time and distance.  The stopping distance d of a car after the brakes have been applied varies directly as the square of the speed r. If a car traveling 60 mph can stop in 200 feet, how fast can a car travel and still stop in 72 feet?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #591162 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=591162\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> if it varies directly as the square of the speed, then d = k * r^2\r<BR>\n" );
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document.write( "when d = 200 and r = 60, the formula becomes 200 = k * 60^2.\r<BR>\n" );
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document.write( "divide both sides of the equatin by 60^2 and you get 200 / 60^2 = k\r<BR>\n" );
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document.write( "simplify to get k = 1/18.\r<BR>\n" );
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document.write( "now that you found k, you can use it to solve the problem.\r<BR>\n" );
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document.write( "d = 72 and you want to know the speed.\r<BR>\n" );
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document.write( "the formula is d = k * r^2\r<BR>\n" );
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document.write( "d = 72 and k = 1/18, so the formula becomes 72 = 1/18 * r^2\r<BR>\n" );
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document.write( "multiply both sides of the equation by 18 and you get 72 * 18 = r^2\r<BR>\n" );
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document.write( "take the square root of both sides of the equation and solve for r to get r = 36 mph.\r<BR>\n" );
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document.write( "when the car is traveling at 36 miles per hour, it can stop in 72 feet.\r<BR>\n" );
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document.write( "when the car is trveling at 60 miles per hour, it can stop in 200 feet.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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