document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=388758>Question 388758</A>: <I><SPAN STYLE=\"word-break: break-all;\"> There is 1.5 L of water in a kettle on a cooking plate of 2.0 KW. It takes 7 minutes to heat the water from 20 C to the poiling point.<BR>\n" );
document.write( "a) How much electrical energy is required ? <BR>\n" );
document.write( "b) What is the efficiency of the heating process </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #275145 by </B><A HREF=/tutors/aboutme.mpl?userid=Jk22><B>Jk22(389)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Jk22><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=Jk22><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=275145\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a) 14/60 kWh = 0.84 MJ\r<BR>\n" );
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document.write( "b) the heat capacity of water is 4180 J/kg/K, hence 1.5 l that is heated by 80 degrees needs an energy of : 4180*1.5*80 = 0.5016 MJ<BR>\n" );
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document.write( "hence the efficiency of the process is : (0.84 - 0.5016)/0.5016 = 67 % </SPAN>\n" );
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