Solution
= Solution
The <Galilean transformation> is
$$
ct'=ct,\qquad x'=x-ut=x-\beta ct.
$$
Therefore
$$
\boxed{
A_{\mathrm N}
=\begin{pmatrix}
1&0\\
-\beta&1
\end{pmatrix}}.
$$
= Solution
The <Galilean transformation> is
$$
ct'=ct,\qquad x'=x-ut=x-\beta ct.
$$
Therefore
$$
\boxed{
A_{\mathrm N}
=\begin{pmatrix}
1&0\\
-\beta&1
\end{pmatrix}}.
$$