document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=52207>Question 52207</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0130676446/algebrahomeworkh></A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> a quake sends out two waves at 8.9km/s and 5.1km/s. a siesmograph records the arrival of the 8.9km/s wave 73 seconds before the 5.1km/s wave. what is the distance from the siesmograph to the center of the quake? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #34864 by </B><A HREF=/tutors/aboutme.mpl?userid=Earlsdon><B>Earlsdon(6294)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Earlsdon><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=34864\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Use the distance formula: d = rt where: d = distance, r = rate (speed), and t = time.<BR>\n" );
document.write( "For the fast wave (8.9 km/s):<BR>\n" );
document.write( "d = (8.9 km/s)t secs.<BR>\n" );
document.write( "For the slower wave (5.1 km/s):<BR>\n" );
document.write( "d = (5.1 km/s)(t+73)secs. (It takes 73 seconds longer for this wave to reach the seismograph)\r<BR>\n" );
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document.write( "Since the distances, d, are the same, you can write:<BR>\n" );
document.write( "(8.9 km/s)t = (5.1 km/s)(t+73)secs. Simplify and solve for t.<BR>\n" );
document.write( "8.9t = 5.1t + 372.3 Subtract 5.1t from both sides of the equation.<BR>\n" );
document.write( "3.8t = 372.3 Divide both sides by 3.8<BR>\n" );
document.write( "t = 98 Rounded to the nearest second. (t = 97.973684...) Now substitute this value of t into either of the two initial equations and solve for d, the distance. Let's do both just to check!\r<BR>\n" );
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document.write( "d = (8.9 km/s)(98 s)<BR>\n" );
document.write( "d = 872.2 km\r<BR>\n" );
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document.write( "d = (5.1 km/s)(98+73) s.<BR>\n" );
document.write( "d = (5.1)(171)<BR>\n" );
document.write( "d = 872.1 km\r<BR>\n" );
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document.write( "The epicenter of the 'quake is 872 km (rounded to the nearest km.) from the seismograph. </SPAN>\n" );
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