\documentclass[11pt]{article}
\usepackage[a4paper,margin=18mm]{geometry}
\usepackage{tikzphysics}
\pagestyle{empty}
\begin{document}
\section*{Connections, parameters, and rotations}
\begin{center}
\begin{tikzpicture}[font=\small]
 \node[beam,beam length=4] (B) {};
 \node[damper,anchor=start,damper position=.7] (D) at (B.end) {};
 \node[physical pendulum,physical pendulum length=2,anchor=pivot,rotate=25] (P) at (B.start) {};
 \fill (P.pivot) circle(2pt);
 \node at (2,-2.1) {Shared mechanical attachment points};
\end{tikzpicture}
\end{center}
\begin{center}
\begin{tikzpicture}[font=\small]
 \node[track,track rough start=20,track rough end=80] (T) {};
 \node[track,track length=3,track rise=0,anchor=start] (U) at (T.end) {};
 \foreach \t in {0,25,50,75,100}{
  \fill (T.surface-\t) circle(1.5pt);
  \draw[->] (T.surface-\t)--(T.normal-\t);
 }
 \node[below=10pt] at (T.south) {Rough region and contact normals};
 \node[below=10pt] at (U.south) {Connected flat track};
\end{tikzpicture}
\end{center}
\begin{center}
\begin{tikzpicture}[font=\small]
 \node[layered tank] (T) {};
 \node at (T.lower-center) {$\rho_1$};
 \node at (T.upper-center) {$\rho_2$};
 \node[capillary tube,capillary sag=-.1,capillary width=.7] (C) at (4,0) {};
 \node[venturi,venturi throat diameter=.35,rotate=15] (V) at (8,0) {};
 \foreach \t in {0,25,50,75,100}{\fill (V.top-\t) circle(1.2pt);}
 \node[below=8pt] at (T.south) {Two liquid layers};
 \node[below=8pt] at (C.south) {Convex meniscus};
 \node[below=12pt] at (V.south) {Rotated Venturi};
\end{tikzpicture}
\end{center}
\clearpage
\section*{Wave modes and percentage samples}
\begin{center}
\begin{tikzpicture}[font=\small]
 \node[closed pipe,pipe mode=2,pipe length=6] (C) {};
 \foreach \i in {0,1}{
  \fill (C.node-\i) circle(2pt);
  \draw (C.antinode-\i) circle(2pt);
 }
 \node[below=14pt] at (C.south) {Closed pipe: third harmonic displacement};
 \node[open pipe,pipe mode=2,pipe length=6] (O) at (0,-2.5) {};
 \foreach \i in {0,1}{\fill (O.node-\i) circle(2pt);}
 \foreach \i in {0,1,2}{\draw (O.antinode-\i) circle(2pt);}
 \node[below=14pt] at (O.south) {Open pipe: second harmonic displacement};
 \node[standing wave,standing wave lobes=4,wave length=6] (S) at (0,-5) {};
 \foreach \i in {0,1,2,3,4}{\fill (S.node-\i) circle(2pt);}
 \foreach \i in {0,1,2,3}{\draw (S.antinode-\i) circle(2pt);}
 \node[below=14pt] at (S.south) {Fixed-end standing wave: four loops};
 \node[longitudinal wave,wave length=6,wave coils=30,wave compression=.8] (L) at (0,-7.5) {};
 \node[below=14pt] at (L.south) {Schematic compression and rarefaction};
\end{tikzpicture}
\end{center}
Filled dots mark displacement nodes; open circles mark antinode positions on the axis.
\end{document}