document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1158496>Question 1158496</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A Train on a straight railway track starts from rest and accelerates at 2.0 m/s2 in 10sec. Then the train covers a distance of 300 m at constant speed for 20 sec until the brakes are applied, stopping the train in a uniform manner in an additional 5.0 s. (a) How far is the train in first 30sec? (b) What is the average velocity of the train for the complete journey? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #837716 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52776)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=837716\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
document.write( "A Train on a straight railway track starts from rest and accelerates at 2.0 m/s2 in 10 sec. <BR>\n" );
document.write( "Then the train covers a distance of 300 m at constant speed for 20 sec until the brakes <BR>\n" );
document.write( "are applied, stopping the train in a uniform manner in an additional 5.0 s. <BR>\n" );
document.write( "(a) How far is the train in first 30sec? <BR>\n" );
document.write( "(b) What is the average velocity of the train for the complete journey?<BR>\n" );
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document.write( "The problem is posed INCORRECTLY: its different parts are not consistent and contradict each other.\r<BR>\n" );
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document.write( "For example, it says \" Then the train covers a distance of 300 m at constant speed for 20 sec \".\r<BR>\n" );
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document.write( "But after 10 seconds, the train has the speed v = at = 2*10 = 20 m/s,<BR>\n" );
document.write( "therefore, in the next 20 seconds, if it moves at the constant speed, <BR>\n" );
document.write( "it covers 20*20 = 400 meters, not 300 meters, as the problem states in the post.\r<BR>\n" );
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document.write( "Therefore, the problem can not be solved under these self-contradictory conditions.\r<BR>\n" );
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document.write( "As posted, it is only good to throw it to the closest garbage bin. Or to re-edit it accordingly.\r<BR>\n" );
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document.write( "There is no need to explain that obvious fact, that under these circumstances, <BR>\n" );
document.write( "the \"solution\", given by the other person, makes no sense, too.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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