\documentclass[tikz]{standalone}\input{pre.tex}\begin{document}\begin{tikzpicture}[
force/.style={>=latex,draw=blue,fill=blue},
% axis/.style={densely dashed,gray,font=\small},
axis/.style={densely dashed,black!60,font=\small},
interface/.style={
pattern = north east lines,
draw = none,
pattern color=gray!60,
},
cargo/.style={
rectangle,
fill=magenta!40,
draw=black!50,
inner sep=2.5mm,
},
spring/.style={
decoration={
aspect=0.3,
segment length=.8mm,
amplitude=2mm,
coil},
decorate,
draw=magenta!70
}
]
\begin{scope}[xscale=-1]
\node[] (b) at (-0.35,0) {};
\node[] (d) at (7,0) {};
% \node[above, yshift=1em] at (b) {$m_1$};
\node[] (c) at (4,0) {};
\node[above, yshift=1em] at (c) {$M$};
\node[above, yshift=1em] at (d) {$m$};
% \draw[interface] (0,2.5) rectangle ++(-0.25,-5);
\draw[spring, decoration={segment length=1.7mm}] (b) -- node[above, yshift=1em, xshift=-0.25em, black] {$k$} (c);
\draw[interface] (-0.25,-0.25) rectangle ++(-0.25,0.7);
\draw[interface] (-0.5,-0.25) rectangle ++(8,-0.25);
\draw[thick] (-0.25, -0.25) coordinate (left) -- ++(0,0.7) (left) -- ++(7.75,0);
\draw[axis, <-] (-0.25,-0.7) node[right] {$+x$} -- ++(7.5,0) ;
\draw (2.25,-0.8) -- ++ (0,0.2) node [below, yshift=-0.5em] {$x$};
\draw (4,-0.8) -- ++ (0,0.2) node [below, yshift=-0.5em] {$0$};
\draw[force,->] (d.west) -- ++(-1,0) node[right] {$\vec{v}_{m}$};
\draw[fill=magenta] (c) circle (0.25);
\draw[fill=magenta] (d) circle (0.25);
\end{scope}
\end{tikzpicture}\end{document}
