Three identical particles are placed on a horizontal smooth table, ...

Three identical particles are placed on a horizontal smooth table, connected with strings as shown. The particle \( B \) is imparted a velocity \( v_{0}=9 \mathrm{~m} / \mathrm{s} \) in horizontal direction perpendicular to the line \( A B C \). The speed (in \( \mathrm{m} / \mathrm{s} \) ) of particle \( A \) when it is about to collide with \( C \).