The problem : 3 identical balls lie on a smooth horizontal surface, the 3rd ball moving with a velocity v while the other 2 are stationary and inter-connected via a taut inelastic string. Ball 3 strikes ball 2 normally making angle = 30 degrees with the string. Energy is conserved. We need to find post-impact velocities and impulsive tension. My attempt : By the usual principle that elastic collisions between identical bodies exchange velocities, ball 3 should become stationary while ball 2 acquires V and a part of it gets canceled by tension which then acts on ball 1 and the final result is such that both balls 1 and 2 move with equal final velocities. However this doesn't match the options given. What exactly am I doing wrong ?