document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1159089>Question 1159089</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Your car’s speedometer is geared to accurately give your speed using a certain tire size: 15” diameter wheels (the metal part) and 4.35” tires (the rubber part).\r<BR>\n" );
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document.write( "(a)   If your car's instruments are properly calibrated, how many times should your tire rotate per second if you are travelling at 55 mi/hr?<BR>\n" );
document.write( "rotations = \r<BR>\n" );
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document.write( "(b)   You buy new 5.25” tires and drive at a constant speed of 60 mph (according to your car’s instrument). However, a cop stops you and claims that you were speeding. How fast did the radar gun clock you moving?<BR>\n" );
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document.write( " mph\r<BR>\n" );
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document.write( "(c)   Then you replace your tires with 3.6” tires. When your speedometer reads 25 mph, how fast are you really moving?<BR>\n" );
document.write( "actual speed = <BR>\n" );
document.write( " mph<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #782252 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=782252\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 55 mi/hr is 80.6667 ft/sec <BR>\n" );
document.write( "C=pi*d<BR>\n" );
document.write( "if the diameter is 23.70 inches (2 rubber parts and the wheel), then the circumference of the tire is 74.45 inches or 6.205 feet<BR>\n" );
document.write( "That would make 13.00 rev/sec for 55 mph or 60/55 *13=14.18 rev/sec at 60 mph\r<BR>\n" );
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document.write( "5.25 inch tires have a diameter of 25.5 inches and a circumference of 80.11 inches or 6.676 feet<BR>\n" );
document.write( "At 14.18 rev/sec, one is now going 94.678  ft/sec or 64.55 mph or 65 mph rounded\r<BR>\n" );
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document.write( "3.6 inch tires now have a diameter 22.2 inches or 69.74 inches circumference or 5.812 feet<BR>\n" );
document.write( "13 rev/sec for 55  mph or 5.909 rev/sec for 25 mph<BR>\n" );
document.write( "with these new tires, 5.812*5.909 is 34.34 ft/sec or 23.42 mph<BR>\n" );
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