document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1160717>Question 1160717</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Suppose you’re driving 90.0 kilometers an hour and suddenly see red flashing lights in the rearview mirror. “Great,” you think, and you pull over, taking 20.0 seconds to come to a stop. What was your average acceleration, in m/sec2? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #784106 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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=784106\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font color=black size=3><BR>\n" );
document.write( "1 minute = 60 seconds<BR>\n" );
document.write( "60 minutes = 3600 seconds (multiply both sides by 60)<BR>\n" );
document.write( "1 hour = 3600 seconds\r<BR>\n" );
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document.write( "To convert from 90 km/hr to km/sec, we divide by 3600<BR>\n" );
document.write( "This is the same as multiplying by (1/3600)<BR>\n" );
document.write( "90 km/hr = (90 km/hr)*(1 hr/3600 sec)<BR>\n" );
document.write( "90 km/hr = (90)*(1/3600) km/sec<BR>\n" );
document.write( "90 km/hr = 0.025 km/sec\r<BR>\n" );
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document.write( "To convert from km/sec to m/sec, we multiply by 1000 since there are 1000 meters in 1 km<BR>\n" );
document.write( "0.025 km/sec = (0.025 km/sec)*(1000 m/1 km)<BR>\n" );
document.write( "0.025 km/sec = (0.025*1000) m/sec<BR>\n" );
document.write( "0.025 km/sec = 25 m/sec\r<BR>\n" );
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document.write( "To wrap things up so far,<BR>\n" );
document.write( "90 km/hr = 25 m/sec\r<BR>\n" );
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document.write( "Vi = initial velocity = 25 m/sec<BR>\n" );
document.write( "Vf = final velocity = 0 m/sec<BR>\n" );
document.write( "t = change in time = 20 seconds\r<BR>\n" );
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document.write( "a = acceleration<BR>\n" );
document.write( "a = (Vf-Vi)/t<BR>\n" );
document.write( "a = (0-25)/20<BR>\n" );
document.write( "a = -25/20<BR>\n" );
document.write( "a = -1.25<BR>\n" );
document.write( "Negative acceleration indicates the object is slowing down. A counter force of the brakes is being applied opposite of the car's initial direction. \r<BR>\n" );
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document.write( "<font color=red size=4>Average acceleration is -1.25 m/sec^2</font><BR>\n" );
document.write( "Every second, the car slows down by 1.25 m/sec.\r<BR>\n" );
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document.write( "Side note: 1.25 m/sec = 4.5 km/hr<BR>\n" );
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