Abstract:
A new integrable (indeed, solvable) model of goldfish type
is identified, and some of its properties are discussed. Its Newtonian
equations of motion read as follows:
\begin{align*}
\ddot z_n={}&\frac{\dot z_n^2}{z_n}+c_1\frac{\dot z_n}{z_n}+
c_2\dot z_n+c_2c_3z_n+c_1c_2+{}
\\[2mm]
&{}+\sum_{m=1,m\ne n}^N\frac{(\dot z_n+c_3z_n+c_1)(\dot z_m+c_3z_m+c_1)}
{z_m}\cdot\frac{z_n+z_m}{z_n-z_m},\quad n=1,\dots,N,
\end{align*}
where $c_1$, $c_2$, and $c_3$ are arbitrary constants,
$z_n\equiv z_n(t)$ are the $N$ dependent variables, $N$
is an arbitrary positive number $(N>1)$, $t$ is the independent variable
{(}“time”{\rm)} and the dots indicate time-differentiations.