pendulum-diagram.tex

%% This example is modified from https://tex.stackexchange.com/a/350635

\documentclass[border={10pt}]{standalone}
\usepackage{tikz}
\usetikzlibrary{patterns}

\begin{document}

\scalebox{3.3}{
\begin{tikzpicture}[thick,>=latex,->]

\begin{scope}
\clip(-5,-2) rectangle (5,5);

\draw[dashed] (0,0)  circle (4.24cm);
\filldraw[white] (-4.3,-4.3) rectangle (4.3,0);
\draw[double distance=1.6mm] (0,0) -- (3,3) node[midway,xshift=4mm,yshift=-2mm]{$\ell$};
\draw[->] (3,3) -- (3,1.5) node[below]{$m\cdot g$};
\draw[fill=white] (-1.2,-1.0) -- (-.5,0) arc(180:360:0.5) -- (1.2,-1.0) -- cycle;
\draw[draw=black,fill=white] (0, 0) circle circle (.3cm);
\draw[draw=black,fill=white] (3,3) circle circle (.3cm);
%% \draw[->] (.6,0) -- (2,0);  %% node[above]{\texttt{x}};
\draw[->] (0,.6) -- (0,2);  %% node[above]{\texttt{y}};
\draw[dashed,->] (0, 1.41412) arc(90:45:1.41412) node[above, yshift=3mm, xshift=-4mm]{$\theta$};
\draw[dashed,->] (0, -0.7) arc(270:135:0.7) node [left, xshift=-2mm, yshift=-2mm]{$\tau$};
\draw[pattern=north east lines] (-1.4,-1.3) rectangle (1.4,-1);
\end{scope}

\end{tikzpicture}
}
\end{document}