document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=665945>Question 665945</A>: <I><SPAN STYLE=\"word-break: break-all;\"> When a car reduces its speed by 18 km/h, its wheels, 200 cm in circumference, take 1 second longer to make 50 revolutions. What was the car`s original speed ? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #414181 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=414181\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> When a car reduces its speed by 18 km/h, its wheels, 200 cm in circumference, take 1 second longer to make 50 revolutions. What was the car`s original speed ?<BR>\n" );
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document.write( "Find how far 50 rev is with a 200 cm circumference wheel, convert to meter<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2850%2A200%29%2F100 ALIGN=MIDDLE  ALT=\"%2850%2A200%29%2F100\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 100 meters<BR>\n" );
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document.write( "let s = original speed in meters/sec<BR>\n" );
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document.write( "Find how many m/sec is 18 km/hr<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2818%2A1000%29%2F3600 ALIGN=MIDDLE  ALT=\"%2818%2A1000%29%2F3600\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 5 m/sec<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(s-5) = the reduced speed in m/sec<BR>\n" );
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document.write( "Write a time equation, time = dist/speed<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=100%2F%28%28s-5%29%29 ALIGN=MIDDLE  ALT=\"100%2F%28%28s-5%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > - <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=100%2Fs ALIGN=MIDDLE  ALT=\"100%2Fs\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 1<BR>\n" );
document.write( "multiply by s(s-5), resulting in<BR>\n" );
document.write( "100s - 100(s-5) = s(s-5)<BR>\n" );
document.write( "100s - 100s + 500 = s^2 - 5s<BR>\n" );
document.write( "combine like terms, arrange as a quadratic equation<BR>\n" );
document.write( "s^2 - 5s - 500 = 0<BR>\n" );
document.write( "Factors to<BR>\n" );
document.write( "(s-25)(s+20) = 0<BR>\n" );
document.write( "The positive solution<BR>\n" );
document.write( "s = 25 m/sec is the original speed<BR>\n" );
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document.write( "Convert to km/h<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2825%2A3600%29%2F1000 ALIGN=MIDDLE  ALT=\"%2825%2A3600%29%2F1000\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 90 km/hr<BR>\n" );
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document.write( "Check this, find the time required to travel 100 m at each speed<BR>\n" );
document.write( "Reduced by 5 m/sec: 100/20 = 5 sec<BR>\n" );
document.write( "Original speed: 100/25 = 4 sec, a 1 second difference </SPAN>\n" );
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