The system shown is initially at rest when the bent bar starts to rotate about the vertical axis AB with constant angular acceleration Alpha(not) =3 rad/ s^2 . The coefficient of static friction between the collar of mass m=2 kg and the bent bar is Us=0.35, and the collar is initially d=70 cm from the spin axis AB. Assuming the motion starts at t=0, determine the time at which the collar starts to to slip relative to it.