document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1083857>Question 1083857</A>: <I><SPAN STYLE=\"word-break: break-all;\"> At a fixed temperature, the resistance R of a wire varies directly as the length 1 and inversely as the square of its diameter d. If the resistance is 1.2 ohm when the diameter is 1 mm and the length is 240 cm, what is the resistance when the diameter is 3 mm and the length is 610 cm? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #697897 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=697897\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the direct variation formula is y = k * x\r<BR>\n" );
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document.write( "the indirect variation formula is y = k / x\r<BR>\n" );
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document.write( "the combined direct and indirect variation formula is z = k * x / y\r<BR>\n" );
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document.write( "replace z with R and replace x with L and replace Y with D^2 and the formula becomes:\r<BR>\n" );
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document.write( "R = k * L / D^2\r<BR>\n" );
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document.write( "R is equal to 1.2 when L is 240 and d is 1.\r<BR>\n" );
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document.write( "formula becomes 1.2 = k * 240 / 1^2\r<BR>\n" );
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document.write( "solve for k to get k = 1.2 * 1^2 / 240 = 1.2 / 240 = .005\r<BR>\n" );
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document.write( "that's the value of k which is the constant of variation.\r<BR>\n" );
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document.write( "it remains the same regardless of the values of R or D or L.\r<BR>\n" );
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document.write( "when d = 3 and L = 610, and k = .005, the formula becomes R = .005 * 610 / 3^2.\r<BR>\n" );
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document.write( "this results in R = .3389 ohms.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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