\documentclass[tikz]{standalone}\input{pre.tex}\begin{document}\begin{tikzpicture}
\draw[fill=magenta!5] plot[domain=0:350, smooth cycle] (\x:3.3+rnd*0.51);
\draw[acceleration,->] (4,0.5) -- node[right]{$\vec{g}$} ++(0,-1);
\draw[] (4,-2) node[magenta]{$\bigodot$} node[above, yshift=0.5em] {$\vec{M}$};
\draw (0,2) node [transform shape, scale=1.5] {$\bigotimes$} node[left, xshift=-0.7em] {$O$} coordinate (o);
\draw[axis, black!30] (o) -- ++(0,-5) coordinate (o');
\draw[axis, black!30] (o) -- ++(45:-5) coordinate (c');
\draw[->, thick, blue] (o) -- node[left, yshift=0.4em]{$\vec{l}$} ++(45:-2) node[black, scale=1.5]{$\times$} node[left, xshift=-0.5em] {$C$} coordinate (c);
\draw pic["$\phi$", draw=orange, <->, angle eccentricity=1.2, angle radius=1cm] {angle=c'--o--o'};
% \draw (3,0) node [transform shape, scale=2,opacity=0.3] {$\times$} node[right, xshift=0.5em] {$O'$};
\draw (0,2) node [transform shape, scale=1.5] {$\bigotimes$} node[left, xshift=-0.7em] {$O$} coordinate (o);
% \fill[magenta] (1,2.5) rectangle ++ (0.3,0.3) node [below] {$dm$};
% \draw[->, blue, thick] (0,0) -- node[left] {$\vec{r}_\perp$} (1,2.5);
% \draw[->, blue, thick] (3,0) -- node[right, below] {$\vec{r}\,'_\perp$} (1.3,2.5);
\end{tikzpicture}\end{document}
