PARAGRAPH – 2
Two particles, \( 1 \) and \( 2 \), each of mass \( m \), are connected by a massless spring, and are on a horizontal frictionless plane, as shown in the figure. Initially, the two particles, with their center of mass at \( x_0 \), are oscillating with amplitude \( a \) and angular frequency \( \omega \). Thus, their positions at time \( t \) are given by \( x_1(t) = (x_0 + d) + a \sin \omega t \) and \( x_2(t) = (x_0 - d) - a \sin \omega t \), respectively, where \( d > 2a \). Particle \( 3 \) of mass \( m \) moves towards this system with speed \( u_0 = a\omega/2 \), and undergoes instantaneous elastic collision with particle \( 2 \), at time \( t_0 \). Finally, particles \( 1 \) and \( 2 \) acquire a center of mass speed \( v_{cm} \) and oscillate with amplitude \( b \) and the same angular frequency \( \omega \).

if the collision occurs at time \( t_0 = 0 \), the value of \( v_{cm}/(a\omega) \) will be ___.