Исходники иллюстрации

\documentclass[tikz]{standalone}\input{pre.tex}\begin{document}\begin{tikzpicture}
    \def\angle{50}
    % \draw (0,2) coordinate (o) circle (2); 
    % \draw (o) circle (0.5); 
    % \draw (0,0) -- (5,6);
    \draw[interface] (-6,6.25) rectangle (6,6);
    \draw[thick] (-6,6) --(6,6);

    \coordinate (cc) at (-6,0);
    \draw[fill=white] (cc) circle (2pt);
    \draw[axis, ->] (cc) -- ++ (\angle:7) node[above,black] {$+n$};

    \draw[axis, ->] (0,0) -- + (0,7) node[above,black] {$+x$};
    \draw[black, dotted] (0,0) coordinate (0) arc (0:90:6);

    \draw[fill,black] (0) ++ (0,4) coordinate (m1) circle (3pt);
    \draw[fill,gray] (0) circle (3pt);



    \draw[fill,black] (cc) ++ (\angle:6) coordinate (m2) circle (3pt);

    \draw[force,->] (m1) -- ++ (0,1) node[right] {$\vec{v}$};
    \draw[force,->] (m1) -- ++ (0,-1) node[right] {$\vec{f}_R$};

    \draw[force,->] (m2) -- ++ (90+\angle:1) node[above] {$\vec{v}$};
    \draw[force,->] (m2) -- ++ (180+\angle:1) node[below] {$\vec{f}_R$};

    \draw[axis, ->] (m2) -- ++ (\angle+90:3.5) node[above,black] {$+\tau$};
    \draw (-5,5) node[scale=1.5] {II};
    \draw (5,5) node[scale=1.5] {I};

    \draw[axis, <->] (4,0) -- node[right, black] {$R$} (4,6);
    \draw[axis] (-6,0) --(6,0);



\end{tikzpicture}\end{document}