\section{Instructor's notes for M-2~~Equilibrium of Forces}\label{sec:M2}

\begin{enumerate}
\item[] \latex{\vspace*{-.08in}} NOTE: This experiment is simple, short, and 
not worth a whole 
laboratory period for most students; however for those having difficulty 
with the concept of vector addition, it may be helpful to use it as Part I 
of the  M3 experiment which follows.  If M2 is assigned as a stand alone 
experiment, the instructor probably should somewhat expand and structure 
the measurements. 
\end{enumerate}\latex{\vspace*{-.05in}}


\noindent OBJECTIVE: To experimentally verify vector addition of forces. \\ 

\noindent APPARATUS:
\begin{enumerate}
\item[] \latex{\vspace*{-.08in}}
Circular horizontal force table with $360^\circ$ scale, pulleys, 
weight hangers, slotted masses, protractor, rulers.
\end{enumerate}\latex{\vspace*{-.05in}}

\begin{figure}[h] \centering 
\includegraphics[width=3.0in]{figs/l103/m02-6.eps}
\caption {The horizontal force table}
\end{figure}
 

\noindent SUGGESTIONS: 
\begin{enumerate}
\item[] \latex{\vspace*{-.08in}}
Choose two concurrent forces, each between 100 and 500 gram 
weight and not in the same direction.  Add these two vectors to find 
the resultant force: use both a
graphical construction and a numerical computation. \\ 

Check your result by setting up the two original forces on the force table, 
and find experimentally the single force which will hold them in 
equilibrium.  Are the values found by the three methods consistent? \\

Repeat the experiment but use three different original forces.
\end{enumerate}\latex{\vspace*{-.05in}}

\noindent
QUESTION: If the weight hangers used all have identical masses, can their 
weight be neglected? \\
