document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=858305>Question 858305</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A train 600 metre long passes a car running at 72 km/hr in same direction in which the train going in 10 seconds. Calculate the speed of the train. <BR>\n" );
document.write( "A. 108km/hr <BR>\n" );
document.write( "B.252 km/hr <BR>\n" );
document.write( "C.162km/hr <BR>\n" );
document.write( "D.225 km/hr </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #517278 by </B><A HREF=/tutors/aboutme.mpl?userid=KMST><B>KMST(5328)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=KMST><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=KMST><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=517278\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> According to my calculations the answer is \"none of the above.\"<BR>\n" );
document.write( " <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" >= speed of the train with respect to the ground, in m/s.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2872km%2F%221+hour%22%29%281000m%2F%221+km%22%29%281hour%2F%223600+seconds%22%29=20m%2F%221+second%22=20m ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" ><IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%22%2F+second%22 ALIGN=MIDDLE  ALT=\"%22%2F+second%22\"   DISABLED_style= \"max-width:90%; height:auto;\" > is the car's speed.<BR>\n" );
document.write( " <BR>\n" );
document.write( "ONE WAY TO CALCULATE IT:<BR>\n" );
document.write( "From the point of view of a passenger in the car,<BR>\n" );
document.write( "the car is not moving, and the train is going past the car at<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x-20 ALIGN=MIDDLE  ALT=\"x-20\"   DISABLED_style= \"max-width:90%; height:auto;\" > m/s.<BR>\n" );
document.write( "One moment the passenger sees the front of the train level with the car,<BR>\n" );
document.write( "and 10 seconds later the passenger seens the back of the train level with the car. Since at that point, the front of the train is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=600+m ALIGN=MIDDLE  ALT=\"600+m\"   DISABLED_style= \"max-width:90%; height:auto;\" > ahead of the car, the apparent speed of the train (from the car passenger's point of view is<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=600m%2F%2210+seconds%22=60 ALIGN=MIDDLE  ALT=\"600m%2F%2210+seconds%22=60\"   DISABLED_style= \"max-width:90%; height:auto;\" >m/s.<BR>\n" );
document.write( "So <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x-20=60 ALIGN=MIDDLE  ALT=\"x-20=60\"   DISABLED_style= \"max-width:90%; height:auto;\" >--><IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=60%2B20 ALIGN=MIDDLE  ALT=\"x=60%2B20\"   DISABLED_style= \"max-width:90%; height:auto;\" >--><IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=80 ALIGN=MIDDLE  ALT=\"x=80\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "So the speed of the train with respect to the ground is 80 m/s.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2880m%2F%221+second%22%29%283600seconds%2F%221+hour%22%29%281km%2F%221000+m%22%29=288km%2F%221+hour%22=288 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" ><IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%22km+%2F+hr%22 ALIGN=MIDDLE  ALT=\"%22km+%2F+hr%22\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( " <BR>\n" );
document.write( "ANOTHER WAY TO SEE IT:<BR>\n" );
document.write( "One moment, the train is level with the car, at a certain spot on the road.<BR>\n" );
document.write( "After <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=10 ALIGN=MIDDLE  ALT=\"10\"   DISABLED_style= \"max-width:90%; height:auto;\" > seconds, at 20m/s, the car is 200 m ahead of that initial spot.<BR>\n" );
document.write( "At the same time, going at a faster rate, the front of the train is many meters ahead of that initial spot.<BR>\n" );
document.write( "The back of the train is now level with the car.<BR>\n" );
document.write( "Since the front of the train is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=600 ALIGN=MIDDLE  ALT=\"600\"   DISABLED_style= \"max-width:90%; height:auto;\" > meters ahead of that,<BR>\n" );
document.write( "the front of the train is 200m + 600 m = 800m ahead of that initial spot where car and train first met.<BR>\n" );
document.write( "The train has covered 800m in 10 seconds, so the speed of the train with respect to the ground is 80 m/s. </SPAN>\n" );
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