A thin rod of mass 0.9 kg and length 1 m is suspended , at rest form one end so that it can freely oscillate in the vertical plane. A particle of move 0.1 kg moving in a striaght line with velcoity 80 n/s hits the rod at is bottom most point and sticks to it (see figure) . The angluar speed ( in rad/s) of the rod immediately after the collision will be .