document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=712662>Question 712662</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The radius of the earth is 6380km.\r<BR>\n" );
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document.write( "a) How far does a point on the equator travel in 24hours?\r<BR>\n" );
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document.write( "b) Find the speed of a point on the equator in m/s. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #438121 by </B><A HREF=/tutors/aboutme.mpl?userid=Simnepi><B>Simnepi(216)</B></A><img src=\"/images/stars/stars-09.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Simnepi><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=Simnepi><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=438121\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a)<BR>\n" );
document.write( "the circumference of a circle = 2 * pi * radius<BR>\n" );
document.write( "since the earth spins once on its axis every 24 hours then a point on the equator will travel a full revolution in that time.<BR>\n" );
document.write( "so  the point will travel 2 * pi * 6380km<BR>\n" );
document.write( "using a calculator<BR>\n" );
document.write( "2 * pi * 6380 = 40086.7222598km<BR>\n" );
document.write( "rounding this to the nearest metre (3 decimal places) gives<BR>\n" );
document.write( "40086.722km<BR>\n" );
document.write( "b)<BR>\n" );
document.write( "now we know how far and we want the speed in metres per second, we have to change 24 hours into seconds<BR>\n" );
document.write( "there are 24 *60 minutes in 24 hours = 1440 minutes<BR>\n" );
document.write( "there are 1440 * 60 seconds in 1440 minutes = 86400 seconds<BR>\n" );
document.write( "since the point travels 40086722 metres in 86400 seconds<BR>\n" );
document.write( "speed = distance divided by time <BR>\n" );
document.write( "giving<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=40086722%2F86400 ALIGN=MIDDLE  ALT=\"40086722%2F86400\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 463.96681713 m/s<BR>\n" );
document.write( "rounding this to 2 d.p. <BR>\n" );
document.write( "the point travels at 463.97 m/s </SPAN>\n" );
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