document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1100855>Question 1100855</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A 9800 kg rocket is traveling east along a horizontal frictionless rail at a velocity of 11 m/s. The rocket is then accelerated uniformly to a velocity of 22 m/s in a time of 0.75 s by the expulsion of hot gases. What is the average force with which the gases are expelled by the rocket? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #715391 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=715391\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font color=\"black\" face=\"times\" size=\"3\"><BR>\n" );
document.write( "One of the kinematics equations is \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "a = (Vf-Vi)/t\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "where,\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "a = acceleration<BR>\n" );
document.write( "Vi = initial velocity<BR>\n" );
document.write( "Vf = final velocity<BR>\n" );
document.write( "t = elapsed time\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "In this case,<BR>\n" );
document.write( "a = unknown (we'll find it shortly)<BR>\n" );
document.write( "Vi = 11 meters per second<BR>\n" );
document.write( "Vf = 22 meters per second<BR>\n" );
document.write( "t = 0.75 seconds\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Plug the three given values into the equation and compute<BR>\n" );
document.write( "a = (Vf-Vi)/t<BR>\n" );
document.write( "a = (22-11)/0.75<BR>\n" );
document.write( "a = 14.667 (accurate to 3 decimal places)\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "The rocket's acceleration in this time frame is roughly 14.667 meters per second per second. Basically each second, the velocity is increasing by roughly 14.667 m/s.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "The mass is given to be 9800 kg, so m = 9800. \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Use both of these values to find the force F. Specifically, we will use Newton's 2nd Law that says F = m*a (force = mass times acceleration)\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "So,<BR>\n" );
document.write( "F = m*a<BR>\n" );
document.write( "F = 9800*14.667<BR>\n" );
document.write( "F = <font color=red>143,736.6</font>\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "The gasses are expelled with an average force of roughly <font color=red>143,736.6 Newtons</font>; which accelerates the rocket from 11 m/s to 22 m/s in a timespan of 0.75 seconds.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Note: if you need a more accurate answer, then use a more accurate value for the acceleration. \r<BR>\n" );
document.write( "\n" );
document.write( "</font> </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );