A Level Physics Notes - Forces and Motion - Newton's Third Law of Motion/TITLE> <META NAME="GENERATOR" CONTENT="OpenOffice.org 3.2 (Unix)"> <META NAME="AUTHOR" CONTENT="Paul Smith"> <META NAME="CREATED" CONTENT="20090908;9120700"> <META NAME="CHANGEDBY" CONTENT="Paul Smith"> <META NAME="CHANGED" CONTENT="20100804;11214800"> <META NAME="DESCRIPTION" CONTENT="a level physics notes - forces and motion - newton's third law of motion"> <META NAME="KEYWORDS" CONTENT="a level physics notes, forces, motion, newtons, third, law, motion"> <STYLE TYPE="text/css">  </STYLE> </HEAD> <BODY LANG="en-GB" DIR="LTR"> <DIV TYPE=HEADER> <P ALIGN=CENTER STYLE="margin-bottom: 0cm"><BR> </P> <P ALIGN=CENTER STYLE="margin-bottom: 0cm"><FONT SIZE=5 STYLE="font-size: 20pt">A Level Physics Notes: Forces and Motion – Newton's Third Law of Motion</FONT></P> <P ALIGN=CENTER STYLE="margin-bottom: 0.5cm"><BR><BR> </P> </DIV> <P>Newton's Third Law of Motion states: To every action there is an equal and opposite reaction.</P> <P>By action, the law means force<IMG SRC="a_level_physics_notes_newtons_third_law_of_motion_html_433cc81d.gif" NAME="Object4" ALIGN=ABSMIDDLE HSPACE=8 WIDTH=19 HEIGHT=18>or impulse<IMG SRC="a_level_physics_notes_newtons_third_law_of_motion_html_14dac871.gif" NAME="Object5" ALIGN=ABSMIDDLE HSPACE=8 WIDTH=18 HEIGHT=18>These are very closely related, since<IMG SRC="a_level_physics_notes_newtons_third_law_of_motion_html_m13cc7ce5.gif" NAME="Object6" ALIGN=ABSMIDDLE HSPACE=8 WIDTH=64 HEIGHT=18>It means basically that if you give something a shove, it shoves back. </P> <P>In a collision there is always an exchange of momentum. If two bodies collide, then each exerts an impulse on the other. The impulses are equal in magnitude and opposite in direction. If a body experiences an impulse, it's momentum<IMG SRC="a_level_physics_notes_newtons_third_law_of_motion_html_264388a1.gif" NAME="Object2" ALIGN=ABSMIDDLE HSPACE=8 WIDTH=19 HEIGHT=18>changes by an amount<IMG SRC="a_level_physics_notes_newtons_third_law_of_motion_html_18c2e8ac.gif" NAME="Object3" ALIGN=ABSMIDDLE HSPACE=8 WIDTH=32 HEIGHT=18>equal to the impulse:</P> <P><IMG SRC="a_level_physics_notes_newtons_third_law_of_motion_html_5d62a9b8.gif" NAME="Object1" ALIGN=ABSMIDDLE HSPACE=8 WIDTH=305 HEIGHT=38></P> <P>The actions must be equal and opposite not only in magnitude but also in nature:</P> <P><P ALIGN=CENTER><IMG SRC="a_level_physics_notes_newtons_third_law_of_motion_html_m43fc84fc.gif" ALIGN=CENTER> </P> <P>If one force is gravitational, so is the other, if one force is electrical, so is the other, if one force is a contact force so is the other etc. Notice that the bodies do not actually have to be in contact. Nor do the accelerations have to be equal in magnitude – only the forces do. For the two masses above the smaller body will have a larger acceleration than the larger, since it's mass is sammler. </P> <P>The forces must act along the same line.</P> <P><P ALIGN=CENTER><IMG SRC="a_level_physics_notes_newtons_third_law_of_motion_html_727fc2e6.gif" ALIGN=CENTER> </P> <P> <DIV TYPE=FOOTER> <P ALIGN=CENTER STYLE="margin-top: 0.5cm; margin-bottom: 0cm"><A HREF="http://www.astarmathsandphysics.com/">Home</A> <A HREF="http://www.astarmathsandphysics.com/maths_and_physics_notes.html">Maths and Physics Notes Home</A> <A HREF="http://www.astarmathsandphysics.com/a_level_physics_notes_menu.html">A Level Physics Notes Home</A> <A HREF="http://www.astarmathsandphysics.com/a_level_physics_notes/a_level_physics_notes_forces_and_motion_menu.html">Forces and Motion Notes Home</A></P> <P ALIGN=CENTER STYLE="margin-bottom: 0cm"><BR> </P> <P ALIGN=CENTER STYLE="margin-bottom: 0cm"><A HREF="http://www.studentforums.biz/">Student Forum</A> <A HREF="http://www.tutoragency.org/">Tutor agency</A></P> </DIV> <SCRIPT SRC="http://www.google-analytics.com/urchin.js"></SCRIPT><SCRIPT> //<![CDATA[ _uacct = "UA-1873754-1"; urchinTracker(); //]]> </SCRIPT> </BODY> </HTML>