<p>A rod of mass M and length L is lying on a horizontal frictionless surface. A particle of mass &#39;m&#39; travelling along the surface hits at one end of the rod with a velocity &#39;u&#39; in a direction perpendicular to the rod. The collision is completely elastic. After collision, particle comes to rest. The ratio of masses&nbsp;<span class="equation">\(\begin{pmatrix}
\frac{m}{M}
\end{pmatrix} is \frac{1}{x}\)</span>. The value of &#39;x&#39; will be____​​​​​​​</p>