diff --git a/public/dyn/multi_body_systems/GearsChains_edited.png b/public/dyn/multi_body_systems/GearsChains_edited.png
index 719d4edfe..215303eb8 100644
Binary files a/public/dyn/multi_body_systems/GearsChains_edited.png and b/public/dyn/multi_body_systems/GearsChains_edited.png differ
diff --git a/src/pages/dyn/coordinate_systems.astro b/src/pages/dyn/coordinate_systems.astro
index 6c1fa8186..6356d74a1 100644
--- a/src/pages/dyn/coordinate_systems.astro
+++ b/src/pages/dyn/coordinate_systems.astro
@@ -23,18 +23,28 @@ import InlineCanvas from "../../components/InlineCanvas.astro"
 ---
 <Layout title = "Coordinate systems" description = "Learn the difference between the cartesian, polar, spherical, and cylindrical coordinate systems">
 
-<div slot="navtree">
+<div slot = "navtree">
   <ul class='list-group list-group-flush py-0'> 
-    <li class='list-group-item py-0'><a class='text-decoration-none subsection' href='#cartesian_coordinate_system'>Cartesian coordinate system</a></li>
-    <li class='list-group-item py-0'><a class='text-decoration-none subsection' href='#polar_coordinate_system'>Polar coordinate system</a></li>
-    <li class='list-group-item py-0'><a class='text-decoration-none subsection' href='#spherical_coordinates'>Spherical coordinates</a></li>
-	<li class='list-group-item py-0'><a class='text-decoration-none subsection' href='#cylindrical_coordinates'>Cylindrical coordinates</a></li>
-</ul>
+    <li class = 'list-group-item py-0'><a class = 'text-decoration-none subsection' href = '#2D'>2D</a>
+      <ul class = 'list-group list-group-flush py-0'>
+        <li class = 'list-group-item py-0'><a class = 'text-decoration-none subsection' href = '#cartesian_coordinate_system'>Cartesian</a></li>
+        <li class = 'list-group-item py-0'><a class = 'text-decoration-none subsection' href = '#polar_coordinate_system'>Polar</a></li>
+      </ul>
+    </li>
+    <li class = 'list-group-item py-0'><a class = 'text-decoration-none subsection' href = '#3D'>3D</a>
+      <ul class = 'list-group list-group-flush py-0'>
+        <li class = 'list-group-item py-0'><a class = 'text-decoration-none subsection' href = '#spherical_coordinate_system'>Spherical</a></li>
+	      <li class = 'list-group-item py-0'><a class = 'text-decoration-none subsection' href = '#cylindrical_coordinate_system'>Cylindrical</a></li>
+      </ul>
+    </li>
+  </ul>
 </div>
 
 <Section title = "Coordinate systems"/>
 
-<SubSection title="Cartesian coordinate system" id="cartesian_coordinate_system">
+<SubSection title = 2D id = "2D"/>
+
+<SubSubSection title = "Cartesian coordinate system" id = "cartesian_coordinate_system">
 
     <p>
         Cartesian coordinates (also known as rectangular
@@ -79,7 +89,9 @@ import InlineCanvas from "../../components/InlineCanvas.astro"
             </p>
         </PrairieDrawCanvas>
     </Center>
-
+    <DisplayEquation equation = `\\begin{align} \\vec{r} &= r_1 \\hat{\\imath} + r_2 \\hat{\\jmath} + r_3 \\hat{k} \\\\
+      \\vec{v} &= \\dot{r}_1 \\hat{\\imath} + \\dot{r}_2 \\hat{\\jmath} + \\dot{r}_3 \\hat{k} \\\\
+      \\vec{a} &= \\ddot{r}_1 \\hat{\\imath} + \\ddot{r}_2 \\hat{\\jmath} + \\ddot{r}_3 \\hat{k} \\end{align}` title = "Position, velocity, and acceleration in cartesian basis." background = "True" id = "cs-c"/>
     <CalloutContainer slot="cards">
         <CalloutCard title="Notation note">
             <p>
@@ -114,9 +126,9 @@ import InlineCanvas from "../../components/InlineCanvas.astro"
               </p>
         </CalloutCard>
     </CalloutContainer>
-</SubSection>
+</SubSubSection>
 
-<SubSection title="Polar coordinate system" id="polar_coordinate_system">
+<SubSubSection title = "Polar coordinate system" id = "polar_coordinate_system">
 
     <p>
         Polar coordinates are an alternative 2D coordinate system
@@ -171,7 +183,9 @@ import InlineCanvas from "../../components/InlineCanvas.astro"
       </p>
 
     <DisplayEquation title="Conversion between polar and Cartesian coordinates" id="rvp-ep" equation = "\\begin{aligned}x &amp;= r \\cos\\theta&amp; r &amp;= \\sqrt{x^2 + y^2} \\\\y &amp;= r \\sin\\theta&amp; \\theta &amp;= \\operatorname{atan2}(y, x)\\end{aligned}" background="True"/>
-
+    <DisplayEquation equation = `\\begin{align} \\vec{r} &= r \\hat{e}_r \\\\
+      \\vec{v} &= \\dot{r} \\hat{e}_r + r \\dot{\\theta} \\hat{e}_\\theta \\\\
+      \\vec{a} &= (\\ddot{r} - r \\dot{\\theta} ^ 2) \\hat{e}_r + (r \\ddot{\\theta} + 2 \\dot{r} \\dot{\\theta}) \\hat{e}_\\theta \\end{align}` title = "Position, velocity and acceleration in polar components." background = "True" id = "cs-p"/>
     <CalloutContainer slot="cards">
         <CalloutCard>
             <p>
@@ -224,9 +238,11 @@ import InlineCanvas from "../../components/InlineCanvas.astro"
               </p>
         </CalloutCard>
     </CalloutContainer>
-</SubSection>
+</SubSubSection>
+
+<SubSection title = "3D" id = "3D"/>
 
-<SubSection title="Spherical coordinates" id="spherical_coordinates">
+<SubSubSection title = "Spherical coordinate system" id = "spherical_coordinate_system">
 
     <p>
       The spherical coordinate system extends polar coordinates
@@ -491,9 +507,9 @@ import InlineCanvas from "../../components/InlineCanvas.astro"
       </p>
     </CalloutCard>
   </CalloutContainer>
-</SubSection>
+</SubSubSection>
 
-<SubSection title="Cylindrical coordinates" id="cylindrical_coordinates">
+<SubSubSection title = "Cylindrical coordinate system" id = "cylindrical_coordinate_system">
 
     <p>
       The cylindrical coordinate system extends polar coordinates into 3D by using the standard vertical coordinate \(z\) for the third.
@@ -698,7 +714,7 @@ import InlineCanvas from "../../components/InlineCanvas.astro"
       vector derivatives</a>.
     </p>
   </DisplayEquation>
-</SubSection>
+</SubSubSection>
 
 
 </Layout>
diff --git a/src/pages/dyn/momentum.astro b/src/pages/dyn/momentum.astro
index e6533c41a..eceb0c709 100644
--- a/src/pages/dyn/momentum.astro
+++ b/src/pages/dyn/momentum.astro
@@ -30,6 +30,7 @@ import Col from "../../components/Col.astro"
 	<li class='list-group-item py-0'><a class='text-decoration-none subsection' href='#momentum'>Momentum</a></li>
 	<li class='list-group-item py-0'><a class='text-decoration-none subsection' href='#impulse'>Impulse</a></li>
 	<li class='list-group-item py-0'><a class='text-decoration-none subsection' href='#collisions'>Collisions</a></li>
+	<li class = 'list-group-item py-0'><a class = 'text-decoration-none subsection' href = '#rotation_about_arbitrary_reference_points'>Rotation about arbitrary reference points</a></li>
   </ul>
 </div>
 
@@ -675,7 +676,61 @@ import Col from "../../components/Col.astro"
 
 </SubSection>
 
-
+  <SubSection title = "Rotation about arbitrary reference points" id = "rotation_about_arbitrary_reference_points">
+    <p>
+      In some cases, using the center of mass as a reference point is not ideal, and we might encounter situations in which we would need to consider the dynamics about another point.
+	  We will begin by finding the angular momentum of a rigid body about any arbitrary point, and extend that from there.
+  	</p>
+  	<DisplayEquation equation = "\\vec{L}_P = \\vec{r}_{PC} \\times m \\vec{v}_C + I_C \\, \\vec{\\omega}" title = "Angular momentum of a rigid body about an arbitrary point \\(P\\)." background = "True" id = "reg-lp"/>
+	<p>
+		We can differentiate the above expression with respect to time and obtain the time derivative of the angular momentum of the rigid body about point \(P\).
+		This will yield two important special cases of rotations. 
+	</p>
+  	<DisplayEquation equation = "\\frac{d \\vec{L}_P}{dt} = \\vec{M}_P - \\vec{r}_{PC} \\times m \\vec{a}_P" title = "Rate of change of angular momentum about an arbitrary point \\(P\\)." background = "True" id = "reg-lt"/>
+	<p>
+		The important special cases are outlined below.
+	</p>
+	<DisplayTable id = "reg-lm">
+		<thead>
+			<tr class = "lineBelow">
+				<th>
+					case
+				</th>
+				<th>
+					result
+				</th>
+				<th>
+					consequence
+				</th>
+			</tr>
+		</thead>
+		<tbody>
+			<tr class = "lineBelow">
+				<th>
+					\(P = C\)
+				</th>
+				<td>
+					<InlineEquation equation = "\\vec{M}_P = \\vec{M}_C = \\frac{d \\vec{L}_C}{dt}"/>
+				</td>
+				<td>
+					This is Euler's 2nd law.
+				</td>
+			</tr>
+			<tr class = "lineBelow">
+				<th>
+					<InlineEquation equation = "\\vec{a}_P = \\vec{0}"/>
+				</th>
+				<td>
+					<InlineEquation equation = "\\vec{M}_P = \\frac{d \\vec{L}_P}{dt}"/>
+				</td>
+				<td>
+					The rigid body is rotating about a fixed point \(P\).
+					This is another form of Euler's 2nd law.
+				</td>
+			</tr>
+		</tbody>
+	</DisplayTable>
+  </SubSection>
 
 </Layout>
 
diff --git a/src/pages/dyn/multi_body_systems.astro b/src/pages/dyn/multi_body_systems.astro
index 3569782f7..00c7c33d7 100644
--- a/src/pages/dyn/multi_body_systems.astro
+++ b/src/pages/dyn/multi_body_systems.astro
@@ -31,6 +31,7 @@ import DisplayTable from "../../components/DisplayTable.astro"
   <ul class='list-group list-group-flush py-0'> 
 	<li class='list-group-item py-0'><a class='text-decoration-none subsection' href='#gears'>Gears</a>
 		    <ul class='list-group list-group-flush py-0'> 
+      <li class = 'list-group-item py-0'><a class = 'text-decoration-none subsubsection' href = '#chains'>Chains</a></li>
             <li class='list-group-item py-0'><a class='text-decoration-none subsubsection' href='#sign_convention'>Standard sign convention</a></li>
 			<li class='list-group-item py-0'><a class='text-decoration-none subsubsection' href='#acce_contact_noslip_convention'>Acceleration in contact (no slip)</a></li>
       <li class = 'list-group-item py-0'><a class = 'text-decoration-none subsubsection' href = '#gear_kinetics'>Gear kinetics</a></li>
@@ -55,11 +56,6 @@ import DisplayTable from "../../components/DisplayTable.astro"
       <li>Accelerations - &gt; tangential are equal but centripetal are not</li>
       <li>Opposite direction</li>
     </ul>
-
-
-    <Image src="/dyn/multi_body_systems/GearsChains_edited.png" width="7"></Image>
-	
-
   <CalloutContainer slot = "cards">
     <CalloutCard title = "Heads up!">
       <p>
@@ -73,6 +69,12 @@ import DisplayTable from "../../components/DisplayTable.astro"
   </CalloutContainer>
 
 </SubSection> 
+
+  <SubSubSection title = "Chains" id = "chains">
+    <Image src = "/dyn/multi_body_systems/GearsChains_edited.png" width = "7"></Image>
+  </SubSubSection>
+
+<!--
 <SubSubSection title="Standard sign convention"  id="sign_convention">
 
     <Image src="/dyn/multi_body_systems/GearsSignConvention.png" width="6"></Image>
@@ -103,12 +105,14 @@ import DisplayTable from "../../components/DisplayTable.astro"
 
 	
 </SubSubSection>
+-->
 
 <SubSubSection title="Acceleration in contact (no slip)"  id="acce_contact_noslip_convention">
 
     <Image src="/dyn/multi_body_systems/GearsContact.png" width="7"></Image>
 </SubSubSection>
 
+<!--
 <SubSubSection title = "Gear kinetics"  id = "gear_kinetics">
     <Image src = "/dyn/multi_body_systems/gear_kinetics.png" width = "3"/>
     <p>
@@ -122,6 +126,7 @@ import DisplayTable from "../../components/DisplayTable.astro"
       </ul>
     </p>
 </SubSubSection>
+-->
 
 <SubSection title = "Four-bar linkages" id = "four_bar_linkages">
   <Image src = "/dyn/multi_body_systems/Crank-Rocker_4-bar_Linkage.gif" width = "5">Image from <a target = "_blank" rel = "noopener noreferrer" href = "https://commons.wikimedia.org/wiki/File:Crank-Rocker_4-bar_Linkage.gif">Wikimedia.</a> CC BY 2.0</Image>
diff --git a/src/pages/dyn/rigid_body_kinetics.astro b/src/pages/dyn/rigid_body_kinetics.astro
index 2f1fbc533..a5de96515 100644
--- a/src/pages/dyn/rigid_body_kinetics.astro
+++ b/src/pages/dyn/rigid_body_kinetics.astro
@@ -29,8 +29,6 @@ import Row from "../../components/Row.astro"
   <ul class='list-group list-group-flush py-0'> 
     <li class='list-group-item py-0'><a class='text-decoration-none subsection' href='#euler-motion'>Euler's laws of motion</a>
     </li>
-    <li class='list-group-item py-0'><a class='text-decoration-none subsection' href='#rotation-arbitrary'>Rotation about arbitrary reference points</a>
-    </li>
   </ul>
 </div>
 
@@ -102,55 +100,15 @@ import Row from "../../components/Row.astro"
     </CalloutContainer>
 
   </SubSection>
-  
-  <SubSection title="Rotation about arbitrary reference points" id="rotation-arbitrary">
-    <p>
-      In some cases, using the center of mass as a reference point is not ideal, and we might encounter
-      situations in which we would need to consider the dynamics about another point. We will begin by
-      finding the angular momentum of a rigid body about any arbitrary point, and extend that from there.
-  </p>
-  
-  <DisplayEquation equation="\\vec{L}_P = \\vec{r}_{PC} \\times m\\vec{v}_C + I_C \\, \\vec\\omega" title="Angular momentum of a rigid body about an arbitrary point \\(P\\)." id="reg-lp" background="True"/>
-  
-  <p>
-    We can differentiate the above expression with respect to time and obtain the time derivative of
-    the angular momentum of the rigid body about point \(P\). This will yield two important special cases of
-    rotations. 
-  </p>
-  
-  <DisplayEquation equation="\\frac{d\\vec{L}_P}{dt} = \\vec{M}_P - \\vec{r}_{PC} \\times m\\vec{a}_P" title="Rate of change of angular momentum about an arbitrary point \\(P\\)." id="reg-lt" background="True"/>
-  
-  <p>
-    The important special cases are outlined below.
-  </p>
-  
-  <DisplayTable id="reg-lm" >
-    <thead>
-      <tr class="lineBelow">
-        <th>case</th>
-        <th>result</th>
-        <th>consequence</th>
-      </tr>
-    </thead>
-    <tbody>
-      <tr class="lineBelow">
-        <th>\(P = C\)</th>
-        <td><InlineEquation equation="\\vec{M}_P = \\vec{M}_C = \\frac{d\\vec{L}_C}{dt}" />      </td>
-        <td>This is Euler's 2nd law.</td>
-      </tr>
-      <tr class="lineBelow">
-        <th><InlineEquation equation="\\vec{a}_P = \\vec{0}" />
-        </th>
-        <td><InlineEquation equation="\\vec{M}_P = \\frac{d\\vec{L}_P}{dt}" />
-        </td>
-        <td>The rigid body is rotating about a fixed point \(P\). This is another
-        form of Euler's 2nd law.</td>
-      </tr>
-    </tbody>
-  </DisplayTable>
-  
-  </SubSection>
 
+    <SubSection title = "Solution steps" id = "solution_steps">
+        The steps involved in analyzing a rigid body mechanical system with Newton's equations are as follows.
+        <DisplayEquation equation = `\\begin{align} &1. \\ \\text{System diagram: draw a system diagram.} \\\\
+            &2. \\ \\text{FBD: draw a free body diagram.} \\\\
+            &3. \\ \\text{Kinematics: determine } \\vec{a}_c, \\vec{a}. \\\\
+            &4. \\ \\text{Kinetics: use} \\sum \\vec{F} = m \\vec{a}_c, \\sum M_{CZ} = I_{CZ} \\alpha_Z. \\\\
+            &5. \\ \\text{Algebra: rearrange and solve as needed.} \\end{align}` background = "True"/>
+    </SubSection>
 
 </Layout>