Momentum Lessons

docs/p30/mom/coll1d.htm

@@ -64,14 +64,14 @@ <h2 class="Collapse">Practice<span data-print="Practice"></span></h2><div class=
             <p class="TeX">\begin{align}E_i &= \frac{1}{2}m_U{v_{iU}}^2
                 \\[10pt] &= \rm {\frac{1}{2} (6.65\times 10^{-27}\ kg) (6.00\times 10^7\ m/s)^2}
                 \\[10pt] &= \rm {1.20\times 10^{-11}\ J}
-        \end{align}</p>
-        <p>Calculate the final mechanical energy:</p>
-        <p class="TeX">\begin{align}E_f &= \frac{1}{2}m_P{v_{fP}}^2 + \frac{1}{2}m_U{v_{fU}}^2
-            \\[10pt] &= \rm {\frac{1}{2} (1.67\times 10^{-27}\ kg) (9.59\times 10^7\ m/s)^2 + \frac{1}{2} (6.65\times 10^{-27}\ kg) (3.59\times 10^7\ m/s)^2}
-            \\[10pt] &= \rm {1.20\times 10^{-11}\ J}
-    \end{align}</p>
-    <p>The collision appears to be elastic because the mechanical energy does not change.</p>
-    </div>
+            \end{align}</p>
+            <p>Calculate the final mechanical energy:</p>
+            <p class="TeX">\begin{align}E_f &= \frac{1}{2}m_P{v_{fP}}^2 + \frac{1}{2}m_U{v_{fU}}^2
+                \\[10pt] &= \rm {\frac{1}{2} (1.67\times 10^{-27}\ kg) (9.59\times 10^7\ m/s)^2 + \frac{1}{2} (6.65\times 10^{-27}\ kg) (3.59\times 10^7\ m/s)^2}
+                \\[10pt] &= \rm {1.20\times 10^{-11}\ J}
+            \end{align}</p>
+            <p>The collision appears to be elastic because the mechanical energy does not change.</p>
+        </div>
     </ol></li>
 
 
@@ -118,6 +118,12 @@ <h2 class="Collapse">Practice<span data-print="Practice"></span></h2><div class=
 <h2 class="Collapse">Review<span data-print="Review"></h2><div class="Collapse">
 <div id="Review">
 <ol>
+    <li>Define <em class="Defn">elastic</em> and <em class="Defn">inelastic</em> collisions.</li>
+    <div class="Answer">Elastic means that mechanical energy as well as momentum is conserved. Inelastic means that only momentum is conserved as some of the mechanical energy is transformed into non-mechanical forms such as sound or thermal energy.</div>
+
+    <li>What does it mean to say that a collision in which the objects remain attached after the collison is “completely” inelastic.</li>
+    <div class="Answer">The loss of mechanical energy is greatest (while momentum is conserved) when the two masses stick together.</div>
+
     <li>A toy train set includes a locomotive of mass of 750 grams and a passenger car of mass 400 grams. The locomotive has an initial velocity of –20.0 cm/s as it backs into the passenger car which is initially at rest. The locomotive and the passenger car do not join together successfully, and the passenger car moves off with a final velocity of –15.0 cm/s. Calculate:<ol type="a">
         <li>the final velocity of the locomotive.</li>
         <div class="Answer">